Any kind of 1/4 map does practice it, lower BPM might be helpful but imo you should play all kinds of BPMs with 1/4 to make sure you learn it all. Some of these are AR8 or 7 so just edit them manually if you hate low AR.
Venetian Snares - My So-Called Life https://osu.ppy.sh/s/243485 170BPM (pretty hard, go into the editor and delete the first third of the map cuz its boring)
When I lay awake at night and can't sleep I do imaginary streams with my fingers. Start out real slow and you can feel the tendons moving in your arms. Scary stuff.