Fly sparging is generally a fair amount slower than batch sparging (I hear 30+ minutes, and not uncommon for 50+ minutes).
Batch sparging is as fast as you want it to be without sticking your sparge . Of course, you then reload your MLT, stir, wait, and drain again. AND, maybe you do this yet again.
I batch sparge and I have a 1/2" full port ball valve, and only open it about 1/4-1/3 way for most of the sparge until I reach the very end at which point I slowly open it fully. I hope this helps.
At 1/4-1/3 open, I still grain my MLT within 5-8 minutes so it's fairly fast IMO.