I'll tell you a little bit of that is just tunneling-forward first with manual performance, daring myself to do chords that are barely in my ability limit, say going 3 seconds then going "ok save" or if i know i have a clear concept but i have to dial the tempo dial on the synth from 120bpm down to 80 or even 60, then back up to get it right. At length hearing my own composition enough times I can then play (some of) the constructions at full speed. But often it only took 1 or 2 takes anyway.