I think I've heard Mylarmelodies say he practices as if he was performing in front of an audience. So just set a time box, lets say one hour, and keep going no matter what.

When jamming I sometimes stop and repatch, tweak a sequence or whatever. I couldn't do that in front of an audience, you can't stop the music and have to keep it interesting over time. I might try this kind of practice next time, it's a bit like sacguy71's mindless patch approach.

Lately I'm also enjoying some podcasts and talks, the one Mylarmelodies did with Surgeon was great, and all the STOOR's Knob Twiddlers Hangout series are also fantastic, even if they are not specific to modular synths.