I mostly see boys change their hair about every 3 or 4 weeks, or possibly a month, but it's up to what they want to do with it.
When your girlfriend makes you.
How often should you change the fuel filter?
Never unless you want to get arrested.
Possibly. In my case, I am more often than I care to admit.
as often as needed
You should change your oil every 3,000 miles. If you drive your car rough, then you should change it more often.
If you are asking this question you are probably getting it wrong. But you should stick with a lot but don't be creepy.
everyday
Have sex with her more often or find ways to please her in bed so well that she wants you instead of the dildo.
How often should you change water pump in a boat
You should change them after every feeding because they should be washed after every feeding.
you should change it every week so it will always be clean.