What is the norm for celebrating First Friday/Saturday Novena Masses on Holy Days of Obligation? When First Fridays or First Saturdays fall on Solemnities (like All Saints is on Friday in 2019), do people usually punt the devotions to the next month or pack them into the same day?
What is the norm for celebrating First Friday/Saturday Novena Masses on Holy Days of Obligation?

These devotions you speak of are not technically novenas and as such the Mass of the day fulfills the need to complete the requirements of these same devotions.

First of all, we must understand what are the First Friday Devotions, the First Saturday Devotions and holy days of obligation (Solemnities):


  First Friday Devotion
  
  The First Friday Devotions are a set of Catholic devotions to especially recognize the Sacred Heart of Jesus, and through it offer reparations for sins. In the visions of Christ reported by Saint Margaret Mary Alacoque in the 17th century, several promises were made to those people who practiced the First Fridays Devotions, one of which included final perseverance.
  
  The devotion consists of several practices that are performed on the first Fridays of nine consecutive months. On these days, a person is to attend Mass and receive Communion. If the need arises, in order to receive Communion in a state of grace, a person should also make use of the Sacrament of Penance before attending Mass. In many Catholic communities the practice of the Holy Hour of meditation during the Exposition of the Blessed Sacrament during the First Fridays is encouraged. - Wikipedia





  First Saturdays Devotion
  
  The First Saturdays Devotion (also called the Act of Reparation to the Immaculate Heart of the Blessed Virgin Mary) is a Catholic devotion which, according to Sister Lúcia of Fátima, was requested by the Virgin Mary in an apparition at Pontevedra, Spain, in December 1925. This devotion has been approved by the Roman Catholic Church.
  
  When Sister Lúcia experienced the Pontevedra apparitions of the Blessed Virgin Mary, she heard her promise to grant great graces, especially at the hour of death, in particular the salvation of the soul, for the believer who for Five Consecutive First Saturdays of Month (5 Saturdays in 5 months) receives Holy Communion and practices the following exercises as an Act of Reparation to the Immaculate Heart of the Blessed Virgin Mary, Mother of God and Queen of Heaven:
  
  
  Sacramental confession
  
  
  The confession can take place within eight days before or even after the Holy Communion is received, but the Holy Communion shall be received with dignity, in a state of Grace, keeping in mind that Jesus is physically present in the Eucharist (Transubstantiation). The Intention of making reparation to the Immaculate Heart of Mary may be kept to oneself; it is not necessary to notify the confessor priest.
  
  
  To receive Holy Communion.
  
  
  The Holy Communion has to be received within the 24 hours of the first Saturday of the Month. Attendance to Holy Mass is optional. Receiving Holy Communion as part of this devotion must be consciously intended as an Act of Reparation to the Immaculate Heart. The devotee need not tell anyone else, but keep it in mind. To avoid omitting the Intention every Saturday, the General Intention for the devotion of the Act of Reparation can be mentally or outspokenly stated before starting the First Saturdays (or in between).
  
  If a person has a valid reason not to attend Mass (Masses not available on Saturdays, difficult mobilization, other major event), the devotee may consult a priest about receiving Communion privately or on another day with the intention of making this Communion as part of the devotion.
  
  
  A 5-Decade Rosary is recited.
  
  
  The Rosary must also be recited with the intention of making reparation.
  
  
  A 15-Minute Meditation is made on the Mysteries of the Rosary.
  
  
  This Meditation should also be done in an Act of Reparation to the Immaculate Heart of Mary. The Rosary Meditations can be recited on all 15 of the mysteries or fewer but must last for 15 minutes. This meditation is in addition (i.e. separated) to the recitation of the Rosary. It can be prayed alone or in a group and with or without the aid of sacred scripture.
  
  The activities of the Five First Saturdays devotions are different from similar devotions on other days in that all should be done with the specific intention in the heart of making reparation to the Blessed Mother for blasphemies against her, her name and her holy initiatives. - Wikipedia





  Holy day of obligation
  
  In the Catholic Church, holy days of obligation (also called holydays, holidays, or days of obligation) are days on which the faithful are expected to attend Mass, and engage in rest from work and recreation, according to the Third Commandment.
  
  The expectation is attached to the holy day, even if transferred, as sometimes happens in the Roman Rite, to another date because of coinciding with a higher-ranking celebration. However, in some countries a dispensation is granted in such circumstances.
  
  The holy days of obligation for Latin Catholics are indicated in canon 1246 of the 1983 Code of Canon Law:
  
  
    Can. 1246. §1. Sunday, on which by apostolic tradition the paschal mystery is celebrated, must be observed in the universal Church as the primordial holy day of obligation. The following days must also be observed: the Nativity of our Lord Jesus Christ, the Epiphany, the Ascension, the Body and Blood of Christ, Holy Mary the Mother of God, her Immaculate Conception, her Assumption, Saint Joseph, Saint Peter and Saint Paul the Apostles, and All Saints.
    
    §2. With the prior approval of the Apostolic See, however, the conference of bishops can suppress some of the holy days of obligation or transfer them to a Sunday.
  
  
  Non-Sunday holy days of obligation all have the rank of solemnity. Accordingly, if in Ordinary Time one of them falls on a Sunday, the Sunday celebration gives way to it; but the Sundays of Advent, Lent and Eastertide take precedence over all solemnities, which are then transferred to another day (but the precept is not). Very occasionally, the Feast of the Sacred Heart may fall on Ss. Peter and Paul's feast day, in which case it takes precedence over the Solemnity of Ss. Peter and Paul; the precept then applies to the feast of the Sacred Heart. - Wikipedia


Seeing that the First (9) Fridays Devotion and the First (5) Saturdays Devotion are exactly that a devotion. If one chooses to perform these devotions in order to obtain the promises attached to them one would have to fulfill the obligation that is mentioned in how to perform the devotion, whether or not a particular First Friday or a First Saturday coincides with a Solemnity or not. This is up to the individual to complete the tasks, practices and prayers regardless of what day it falls on.

A holy day of obligation makes no difference in performance of these devotions. One must do nine (9) consecutive First Fridays or Five (5) First Saturdays in a row. If one misses one day, one would have to start all over again.