What is the difference in usage between the pairs 依然/仍然 and 依旧/仍旧? As in the ones with 然 and 旧

Very hard to tell from example sentences

他仍旧住在那老房子里。 He still lived in the old house.
他仍然住在那条街上。 He is still living on that street.

有些问题仍旧没有解决。 Some problems remain to be solved.
我仍然相信他是无辜的。 I still believe he's innocent.

etc...

Is it that one is relative to a shorter time and one is relative to a longer time?
仍旧 means 'still (as always/ same as the past)'
依旧/仍旧 is more specific term for 'still'. It express something 'stay the same despite passing of time '

Example 1 : 五十年过去了, 他仍旧住在那条街上 (fifty years is a long time)
Example 2 : 三年过去了, 我仍旧相信他是无辜的 (three years have passed, nothing changed, I still believe he is innocent)

仍然 means 'still (despite of)'
依然/仍然 is more general term for 'still'. It express something 'stay the same despite any opposing force or reason'

Example 3 : 五十年过去了, 他仍然住在那条街上 (despite the fact that many things would had been changed in 50 years)
Example 4 : 尽管有这么多证据,我仍然相信他是无辜的 (despite the fact that all the evidences are against him, I still believe he is innocent)


*仍旧/依旧 is actually a shortened form of 依然如旧 / 仍然如旧(still like always/ still like before/ still like in the past)

Although they can be used interchangeably sometimes, they are not synonyms.