My daughter is 5 and the redness she gets after a laser tx takes 12 weeks or more to fade. You are also correct in saying that pws is affected by mood, health, temperature etc.
Now she has very bad exzema on her pws since her last tx,so I really have no idea if she had any additional fading. sigh
My daughter has had very good success though. She has had a lot of tx's though to get to this point. We began tx at six weeks old and her Dr was very aggressive. We have switched to maintenance tx for her, meaning that it has gotten at light as it will get at this point, with the current technology and we just do a yearly tx to help keep it this light and help keep progression at bay.