Many folks feed their chickens once a day. It would be fine to just feed in the afternoon or even the evening, as long as they have enough time to eat their fill before they go off to roost (before dusk). I have read from many folks who have withheld feed 12-24 hours from chickens ready for butcher only to find their crops packed full of feed!
Since I hate to measure things (and our flock is constantly growing and shrinking these days!), I don't do the once-a-day-feeding way. Also, some fermented feeders feed 100% fermented feed. I don't and here is why:
* I don't like to mess with the fermented feed daily (other than feeding) or more than once every couple weeks. I mix up a batch at a time every couple weeks. I don't have water near my coops to mix in more feed and water every day or every few days.
* The feed will get more acidic over time as it ferments. I am not a chicken nutrition expert, but I don't believe this is necessarily good for the chickens to get too much acid in their diet. By the end of the two weeks when I am ready to make more, my feed is pretty sour. They seem to eat less of it when it gets that sour.
* Therefore, I also feed some dry feed, in fact, most of their diet is dry feed, I only feed about 10-20% of their diet as fermented feed. The reasons why I do this are varied and more than I want to get into right now, but this is what works for me. They also free range much of the day in non-snow months.
So yes, it's fine to also give them free-choice pellets.
Good for you for giving your chickens some upgraded nutrition with fermented feed!