To me it would be better if the free daily chapter was released based on the current chapter you are reading.
Imagine that you have a new premium novel that releases 2 chapters daily, one locked and one free, after 50 days there would be 50 locked chapters and 50 free chapters. Now imagine someone who is only reading the free chapters but at this point the story is getting interesting and decides to spend some money to read the locked chapters, wouldn't be nice if the next day he gets the chapter 101 free and the chapter 102 locked?
Because to me the problem with the premium novels is that there is no middle ground. either you are all in or all out.