We can tip the same author only once a day and can tip a total of 7-8 times. This is what I think from my usage of past one month.
Yeah, the way publish0x works is if you get featured to front page you gain a lot of followers and then they start tipping you back. Also, you need to figure out when more people are active so we can get more engagement on our articles. Example my articles do relatively good if I post in the morning. By the night most of the users have probably used all their tips so night posts don't do much good.
Indeed, I figured the time of the day was very important.
Thanks for the information on the exact Tip number !