Firstly, you're overshooting STP for non-ionis areas.
Second, ionis does not give Store TP, it gives SAVE TP.
Third, you should post your set so people can give you suggestions.
880 isn't terrible or anything, but it is definitely shy of the 940-960 target for a max accuracy set. Is your GKT skill capped? 8/8 GKT merits? Hasso up? Subjob?
youre either asking if that one set is effective (we dont know for what) or that you only have that one set and want to know if its good enough for everything? if youre only using one set for all events then youre doing it wrong. you should create sets for acc in tiers, at the very least 4. low medium max hybrid/dtAcc. a ws set for each tier of acc would be nice as well. so use your equipment to come up with the best 3 (4 if you count the hyb/dtAcc) tp sets you can with acc as the focus of increase.
do that and then come back and post each set and youll get some good responses. this way, youll have every situation geared so people wont ask "for what event?" as much.
Getting above 900~ is around when you have to start making large sacrifices like Windbuffet+1 to Anguinus/Olseni, Bladeborn to Zennaroi, rings to Ramuh+1s, etc. Usually you'd just want to use that 880~ acc set and use proper buffs to compensate, of course there are events like Incursion that you do need every bit of accuracy.
the difference in gear sets you need for varying levels of incursion are vastly different, let alone the original delves. it entirely depends on what buffs/debuffs are present and no one set is ideal. as bukadan said, you should be aiming to have sets of varying accuracy (one for capped accuracy, one for a little bit below cap, and one for way the *** below cap) along with accompanying WS sets.
wait I thought you were a mnk. wait skipped that one
I think if you can get to 900 and still have your hit build without loosing haste it should be good to higher content. now remember that its important to have more then 1 set since you wont always need that acc and it goes to waste. so its best to have a low level set and a higher level set.