Once you bounce your MIDI tracks to audio, you can't touch the patches anymore.
No more "let me just adjust this one articulation" at midnight.
It locks the arrangement and forces you into mixing mode, which is exactly where you need to be to finish. If your sessions are full of VST instruments you keep reopening and re-tweaking, this is the fix.
Commit, bounce, move on.
Comment "bounced" if you're going to try this on your current project this week and let me know if you actually do this on every session!