Only bled bikes but the reservoir caps always had a tiny hole to release the pressure that would build up when the brake fluid was backed up by opening the pistons to make room for new pads
Well you know the fluid goes both ways albeit slowly - its all a pressure thing. I don't think levering the pads back will cause a problem if like anything else you do it slowly and carefully. I would rather do this than open the bleed valve and possibly let air in the system.
If you want a bit of practical advice (why give too much advice you learn by doing and making mistakes - go slowly and use common sense) its dont top up the master cylinder before you push the pads back as it will overflow...weve all done it
Im not denying that your brakes are important but the flip side is they are the easiest part of your car to work on and they use very simple principles.
Sorry if this upsets the H&S self righteous
