I think your timings are very generous.

Don't forget that the malls are not comparable to the malls in say Dubai. The Museum of Modern Art I did in 2 hours, but I am also not really the type who studies every carpet for 20mins. You can do everything in 1,5 days in my opinion.

Assuming you have access to the proper QR lounges, I would go even earlier (but I can easily spend six / seven hours in the lounge )