How long is it safe to leave nail polish on for?

I would say that nail varnish stays on for about a week, but sometimes longer.....it depends, but heat/hot water etc does weaken the nails and make them chip etc. As false nails, nail varnish also grows with your nails. It is important that when you are putting nail varnish on that you dont go right to the cutical and around the edge of your nails as that makes them chip, and they dont last as long. If you cover your nail varnish with clear nail varnish, then they have a chance of staying on longer.