I'd say about 15-20 mins. Clearly much quicker if I'm not washing my hair, but you know got to wash it, condition it, much manly talk occurring etc. Don't really stand gormless under the hot water, if I have a bath, which is incredibly rare, I'll lay it that for about 20-30 mins, but then have a shower to get clean, don't like the idea of cleaning myself in my own filth lol, bath is just for relaxing in hot water.