Since my company's insurance provides annual full body check up, that's how often I do it. I feel this is important because I would very much rather find it out in early stages than too late because I have too many responsibilities towards my kids. So it's important that I know my health is good.
If your finance allows, it is recommended to do it annually and if not, every 5 years until the age of 40 and every 1-3 years thereafter. For pap smear it will be good if it is done annually.