It's never a bad idea to top up pressure before every ride when using high pressure road bike tires. Their thin tubes tend to lose pressure much quicker, and they have a narrower range of pressure within which they can operate efficiently. That being said, pressure doesn't have to be an absolutely exact number. You usually can go a few days without topping up. I'm thinking of 2 or 3 days. But it depends. You sort of have to see for yourself how long your tire and tube combination loses pressure.