there's different ways of washing, the best way to wash for warriors is to put AP into HP when u level up, then use resets to take out MP into STR. Not 100% sure on this but this is how I did it and it seemed to give me 50ish hp per wash. What you're doing is probably you put one AP into HP then wash MP into HP continuously.
This is not true. Warriors get 50-54 HP with the first method you described. The other method you described gives 50-55 HP. https://royals.ms/forum/threads/hp-washing-reference-table.17093/ As for why OP is getting less than expected, I can think of two things: 1. He's not looking at the actual gained HP, but at the value that the AP reset claims. 2. He doesn't have the skill Improving Max HP maxed.