How often should you wash your hair?

Once a week. But I spend a lot of time styling it nicely so that it lasts. I think your hair gets used to being washed too much and you can train it to last longer between washes. Or maybe it's training yourself to not mind so much!
To be fair, on the last day before hair washing it doesn't usually look fabulous and if I've got a special occasion I'll cheat and do it a day or two early.

Generally Monday, Wednesday and Friday unless I going anywhere n Saturday

Tuesdays and Fridays.

I was ready recently that it is a bit of a fallacy to leave you hair to cleanse itself. The article said that the oil and yeast make for an itchy scalp and attracts bacteria.

Sometimes every day sometimes every other day, about 4yrs ago I tried leaving mine longer and longer to see if it made any difference to how my how felt/looked apart from on the 3rd day I hated the feel of it and it was lank and itchy so I went back to my usual practice of every other day mostly.