Replacing front brakes pads

I've watched several YouTube videos about replacing front brake pads without removing the calipers. I've done this in the past on other vehicles but have always removed the cap on the master cylinder before compressing the brake pistons to allow room for the new pads. In none of the videos I've watched do any of them mention removing the cap on the master cylinder. Is this necessary or just an old wives tail?

 

I never have...

 

Probably not needed in these but I open it anyway since I flush the fluid when I change pads.

 

I do it as a common practice.

I also remove the calipers bc its easier to compress the pistons back with the proper tool. If you turn the wheels then you can zip the two bolts off with an impact.

Make sure you replace the slides and get some anti-squeel paste for the back of the pads too.

 

Also never have needed to open the reservoir cap to change pads.

But with that said, unless I'm swapping out fresh pads for something else because I didn't like them, I generally change the rotors and pads together and flush the fluid out at the same time.