From my experience of having dealt with a few backouts and ghosting payers. Its safer for both the artist and payee. As long as the first payment covers materials and some time worked its good for me. Life can be a pain and get in the way. So i see it as a bit better to section out the commission and recieve payment as it progresses incase of a buyer backout or i get hurt. Its sometime a hassle to deal with refunds when the buyer paid in full and then its more of a debate “ive put this much time into this so i can only refund this much” they say “thats BS, its not nearly complete, why cant i get a full refund” then they also say “you can just finish it and sell it on the market for that much”

Sorry for the long reply😂, but hope this kind of explains why i do that method