During the winter you're likely to fly about one day for each three you book. So to fly three days a week you'd have to book nine ... er ...
I'd think in practice the answer is that yes, you could do it if you treated it as a full time task, and no, you couldn't do it if you treated it as something to do at weekends.
So, if you need to work to earn a living at the same time, you might proceed as follows:
(1) Arrange with your employer that you can work weekends, and that you can take time off at any time with zero notice. This is OK in jobs where what's important is to get something done, rather than to be seen to be in a particular place at a particular time.
(2) Book to go flying every day.
(3) On the two thirds of days when flying turns out not to be possible, go to work, even if it is Sunday.
[Edited to add: of course this only works if you don't also have some sort of real life to get on with!]