Varying Sets and Reps for Squat

How should I vary the reps and sets for my squat every week?

i’ve been doing 5x5 for the first 2 weeks and starting today (Monday) it will be my 3rd week into the program. Should I keep doing 5x5? Lets say I change it to 5x4, since I took away one rep, does that mean instead of adding 5 pounds to my squat, I add 10 since one rep was taken away? You guys get me?

Also, In Kelly’s NO BS Speed book, he says that you take a deloading week about every 4 weeks…My question is this…During the 4 weeks your training, Should you go real hard during those 4 weeks and then take the deloading week, or…Go real hard for 3 weeks, take it easy on the 4th week and then deload. Should I just go based on how my body feels each week?