In the winter (confess) I dont tend too as imagine having water "put up there" but in the summer 3 or 4 times - depending on if I notice it grubby/smelly... I dont have set willy washing timetable
I use barrier lavender wash (on everything) and a sponge with luke warm water and sometimes a rubber glove covered hand is better for "feeling" dirt.... NICE
Never. I have a quick inspection quite frequently (because he'll flop it out whenever he's relaxed) but its always lovely and clean so I've never had to bother yet.
Cairo - used to have a spring clean with a little sheath cleaner and then through the summer would squirt hose up it, rub my hand to get any lumps off and then rinsed again. Left in winter.
Chancer - has the most horrible willy ever. Needs to be cleaned frequently and have beans removed every couple of months before they get too big. In summer it is hosed weekly and I use my hand to get the worst of the greasy gunk out but don't use anything other than water. Not helped by the fact he rubs his belly and fills it full of dirt.
In winter, I do it every couple of weeks - little warm water and my hand - just enough to stop black gunk down the legs. He too gets a spring clean with a little sheath cleaner but then nothing other than water.
So glad we have now got another mare so I only have one todger to deal with. I am very lucky in that Chancer likes have his done and often dangles it out when relaxed or having his dinner.
As and when it needs it. I never found a sheath cleaner that is that good, do find that a spray of baby oil evar now and then when he's got it out keeps it pretty clean.