Not perhaps personally, but you know of people who are violating your formula. For example, Bruce Willis (54) is married to model Emma Heming (31) and no one cares. I thought the formula was x2-7
I think a formula would be better, but probably a x/3 + 9 would be a little better than drakes formula as it allows more age difference for older people and bans sex for a ages under about 14 years effectively.