I like using been, I listened to a podcast where a linguist explained how versatile it was. If you shorten it that means it like happened in the past and it's continuing to happen and you say it with more like emphasis, maybe like more plosive like a 'P':

"He been playing Mario Kart 8. Mans can't put the joycon down!"

Like you are doing something now or started recently if you say it kinda neutral:

"Yeah, I been tryna find some piece to play, I just keep on playin' Chopin, boy's been havin' it since 1818 or something. Old man and it's been a while since he dead, but he wasn't ok with dyin' cuz he's been killin' it.

Maybe like sarcastically or when you lengthen it:

A: "You do your part of the assignment? I haven't started I went to see Speed since it was playing."
B: "You were watching a re-run of some old movie no one's heard? Well, I've been doing my homework, y'know, what was assigned and we agreed to do."