How to check completeness of a bought set? Trying to solve problem for which I asked help in Looks like total number of parts and sum of them differs on bricklink I understood I did not have the skills to check contents of a set.  I did Web search for "site:bricks.stackexchange.com how to check completeness of a bought set" and did not find relevant info so making new post.  The question How to check the missing pieces of a given set? is titled similarly, but asks about different thing from mine.

Initially I tried to count parts by tens, put them in one place and keep count of tens.  I miscounted set of 602 by about 10‰ of parts. Then I tried to go by bricklink list again keeping track in tens. Again I failed though twice less.  

Finally I separated parts by each "type",  taking large area on the floor and going by bricklink list I glanced at the parts,  checked presence and added up. On that way I found several occasions where I misplaced parts, but finally I got exact count, so I bought complete set as expected. Picture of layout below:  

What are your favorite ways to check completeness of bought sets?
You've already discovered yourself two good ways:


count by ten
put elements on large surface by type


The latter technique can be extended to an art called "knolling":


Place all elements by type in right lines with right angles on a large surface...
Its a very relaxing exercise and fun in its own right. Checking completeness becomes trivial, building afterwards can also be done with much less frustration.

Update: Here's another very impressive knolling. The UCS Millenium Falcon 75192 
 (7541 pieces) https://i.redd.it/q51wrtua5yb41.jpg 
(can't insert picture here directly since too large)