As badly mangled as canon is on hyperspace is anyways, it's more or less applied phlebotenum anyways. Let's take the parts separately and discuss
Current canon is that hyperspace is imprecise
There's both microjumps and Hyperspace skipping. Neither are considered easy to do (or safe), or we'd see them in use a lot more often. But they do exist
Poe was reckless and what he did was dangerous
We don't have to theorize here. Nobody seems keen on it in Rise of Skywalker and considering the Millennium Falcon barely survives, it wasn't a good idea... but it worked. Somehow. (Transcript)
FINN: What are you dong?!
POE: Lightspeed skipping.
FINN: How do you know how to do that?
POE: Yeah, well, Rey's not here, is she?
POE: Last jump, maybe forever.
POE: Hold on!!!
REY: You lightspeed skipped??
POE: Yeah, well, it got us back here, didn't it?
REY: Poe, the compressor's down.
POE: Oh, I know, I was there.
FINN: Every time.
REY: You can't lightspeed skip the Falcon!
POE: Actually, it turns out you can.
Calculations avoid collisions
The StarWars.com databank says this
Large objects in normal space cast “mass shadows” in hyperspace, so hyperspace jumps must be precisely calculated to avoid collisions.
Which lines up with Han's line to Luke (transcript)
HAN: Traveling through hyperspace isn't like dusting crops, boy! Without precise calculations we could fly right through a star or bounce too close to a supernova and that'd end your trip real quick, wouldn't it?
Han is probably playing it cool (it's just a pesky star destroyer, Luke. Stop whining!), but does need some calculations to make it safely.
Poe is likely rolling the die with his hyperspace skipping maneuvers. He apparently knows enough to make it work, but just barely enough not to get killed in the process. There's no indication the navicomputer was ever upgraded, people just seem to have gotten more reckless over time. From The Force Awakens (transcript)
HAN: Watch the thrust, we're goin' out of here at lightspeed --
REY: (SHOCKED) From inside the hangar? Is that even possible?
HAN: I never ask that question until after I've done it.
So... calculations aren't entirely necessary after all... maybe...