Not in every case.
Power Girl's connection to the post-Crisis Superman and the JSA was never really clear. Pre-Crisis it made sense JSA member Kal-L as her cousin was her in to the JSA. Post-Crisis just what reason was there for this hero with no WW II connection to join that team as opposed to the Titans, League, or another team?
Who did Superman fight on New Earth prior to Crisis since all of his major foes were reintroduced for the first time in stories set after the Crisis despite his being stated as a long established hero by this point in the new history.
How did Mon-El fit into the whole Pocket-Universe story. His Superboy history required him being in the Pocket Universe Phantom Zone but crossing over to the "real" Earth to join the Legion- but somehow being unaware of the difference.
There were other little things like that (who replaced Diana in JSA history, just how the originals reacted to their "Silver Age" replacements, …) which were never answered, but sort of brushed aside so we could move forward. I'm wondering what the TV shows will leave unaddressed so they can move forward and what they will actually investigate/explain.