Cpu limit is a daily limit.
Upgrade to paid hosting then you won't have this daily limitation.
Note: CPU limit is not the same as memory limit
If your site hit the limit daily your site will be redirected daily unless you tune down your site or upgrade to paid hosting
There is no limit to a number of visitors per day but it does impact the CPU limit such as the crawler.
Please read my FAQ on the frequently ask question for more info.