Do you guys have a main that you stick with or do you just play whoever whenever you want?

I've been looking at my characters played in past seasons and notice that I always hop around between characters. Because of this I think I'm not really improving as much as I can since after I switch characters I end up not remembering how to play them optimally. I've spectated and checked some other people's profiles after getting demolished by then and see that they have hundreds of games on one or two agents which is what gave me this idea to begin with.

I'm between gold and plat with 1 win from getting into plat but I haven't done it yet since I wanna improve more before tackling higher ranks. Would y'all recommend me to fill or play one or two agents to improve and if so who.