2 questions: How long did it take? And how did you do it?

Throw rocks in a pond

I got to 96%. I could never figure out what the other 4 percent was. I would say do a second playthrpugh or get the first game and continue the storyline from John. You should be able to get it on pc, and rockstar did a remake for Nintendo switch

It took me about 2 weeks I think, most of them I completed through story

Used save cheats method in chapter 4

And the Exotics one I just looked up methods how to spawn birds fast and where flowers spawn (Also if you collect the flowers before starting the quest, the final flower won't spawn until you talk to Algernon)

do it again but make visiting arthurs grave the final one

Play something else like Cyberpunk, GTA or FO4/76.

Just ride around.

Gamble all your money away

Do crimes and find was to unalive yourself in the game