I've working on the speed of my single strokes lately by doing the "Singles Pyramid" which I learned from #HueyYanPan via his Periscope broadcasts. I began playing at 86 b.p.m.s a week or so ago, now I'm up to 92 b.p.m.
My goal is 100! Thanks Huei!
Check out his Twitter posts @hueiyanpan.