If you are simply planning to help people to get some free satoshis, then It really doesn't matter, you can do whatever fits you. If you are looking to earn money from this then It's best to make people comeback each a few minutes because coming once a day = less traffic, and If you have less traffic, less people click your ads which means less income for you.
Ok! got it, thanks for your review & opinion.
I am thinking of one per hour based and one per 2 hour based.
Reff % can be between 40% - 60%.
