HP5 at ISO 400 is forgiving, which makes it a good film to keep notes on. My baseline is Ilfosol 3 at 1+9, 20 °C, 6 minutes 30 seconds.
Agitation: continuous for the first 10 seconds, then four inversions every minute. Stop bath with plain water, three changes. Fixer for 5 minutes, then a long wash.
Shadows hold up well; highlights only block when I over-agitate. Next roll: try 1+14 for a little more acutance.