i tend to only wash when i do a full de bond,
as i use orwg, which is water based any or to much water will soften the bond,
having seid that if im lazey, ill do the front half, if the backs pretty good,there tends to be a build up of hairspray on the front,
so ill wash the front, reflect it back to do a scalp clean up,
great advantage of this is theres no lining up the peice,
i think if you want to clean the peice, you can only do it effectively,whilst its not on youre head,
its a compromise between losing the hairline bond if you expose,
then the peice becoming so loose whilst shampooing that you decide to hell with it i may as well take it off and do a full clean up,
i think there are solvent based glues that are more resistant to moisture,
i look forward to hear other folks on the head washing routines, little tipps tricks
still learning*****
anty