When they were smaller and in a smaller brooder, I did it every day, fully. Now, they are in a big, 4 X 5 brooder, and I do it every 4 days or so. I am moving them to the coop very soon, and it is not soon enough. They are getting big.
I should add, I do water and feed every day. Also, I have a wonderful outside enclosure set up out of a dog x pen, with chicken wire covering the top. I use the step in door to put them in and out. They love being out there, so that is where they go while I clean. I have 12 chicks, so it takes me a bit of walking back and forth to put them all out there. Our weather has been wonderful, so they stay out there for a while, even after I am done cleaning.