It is important to understand how the transdermal drug delivery system works. The skin contact side of the patch has a membrane that has very tiny, microscopic, holes in it that allow a metered amount of the narcotic to pass through it and through the skin. Heating the patch or applying pressure to the top of it can increase the amount of narcotic transferred through the skin. Hot water can also compromise the adhesive and cause less drugs to be transferred after the shower or whatever.

The reason why I mention the instructions are that, several years ago, a well meaning member suggested cutting a patch in half as part of the tapering off process. This could release all of the contents at once and cause an instantaneous overdose.
As i have previously stated Fentanyl is safe and effective if used as directed. Misused, it can kill you.

The patches must be applied meticulously to dry, hairless skin to work effectively. The skin should be cleaned with alcohol and allowed to dry before application. Be careful not to touch the adhesive side of the patch - the body oil in your fingers can compromise the adhesion and transference.

The narcotic inside should be substantially depleted at the end of 72 hours, so leaving it on longer isn't going to improve its effectiveness.

I agree that the instructions can be confusing and daunting, especially since the FDA requirement is that EVERY adverse effect be listed - proven or not! Your pharmacist should be able to tell you the real risks and appropriate instructions for use.