I don't prewash but rinse between developer, bleach and fix with 2x fresh (tap) water. Agitation is something like 1x every 15 - 60 seconds, I'm not very meticulous with that, but try to keep short intervals. Dev at room temp between 20 and 30 °C with adjusted times, no streaks, no color shift, perfect developments, be it 135 or 120 film.