1-1.5 hours. Any longer than that and it needs to be outside because there's no way in hell my ADHD/ADD/SAD brain can stand it.

In my book, the rollers are good for 2X20's (or 30 sometimes), 3X3's and HC because that's usually only a short time. ST or anything at an intensity that allows enough O2 to make its way to my squash for superfluous thoughts to occur... forget it.