[DONVITO]

Also there is no need to remove the brake fluid reservoir when compressing the caliper pistons.

Thats not always true. If the pads get so low someone in the past may have topped off the fluid, then when compressing the pads, would cause an over flow from the reservoir. Besides its always a good idea to pop the cap and check the fluid.
If one doesnt have a vacuum bleeder and you had to remove excess fluid, you can use a lint free towel and blot the level down.

 

[DONVITO]

Nope not buying it. Whenever a vehicle is in a shop for inspections when they check and adjust fluids they usually top off the brake fluid because of low pads. Case in point. My son bought a used 2012 tacoma he comes by and says the brakes are squealing. I tak a look and they are below the max wear limit. After compressing the first caliper pistons the fluid level was at the bottom of the cap, and I still had the other side to do. Any shop that pad slaps and not check the fluid condition and level is not very good. Period Ive been in the business so long to know that is a no brainer.

 

[DONVITO]

That makes sense because you pushed the first piston in completely. If you pumped the brake pedal after you completed the one side you would've seen the fluid at a lower level. You have to remember that the pistons when operating normal, don't return completely into the caliper which is where the different fluid level will come into play. If they completely compressed everytime you took your foot off the brake then it would feel as though you had a spongy pedal. I've been a mechanic for 25 years and never had a problem. I will say though that it is necessary to flush the brake fluid from time to time because it can and does get contaminated

I wasnt talking about after pushing the pistons all the way back, I understand the level will be high and when you reset the pedal the level will go down to the correct level. In the case of the Tacoma I still had to remove fluid because it was too high, so somewhere someone added fluid as the pads got lower.
My point of my comment was that you should always check the fluid when changing pads, not just pad slap and be done with it, thats what I was alluding to. Thats how you can find contamination especially when you find someone that thought dot 3 and 5 mixes together.