You only need apply it where the pan is actually leaking. Clean the area very well with brake cleaner first. As I said, I over-applied it; however, who really cares, as no one will see it except you. The product sealed a gas tank on an Alfa Romeo that I owned and showed no signs of failure after several years.
What did I "do" to my car specifically? Your reaction makes it sound as if some permanent damage was done to the car; quite the contrary, it is preventing damage and is 100% reversible upon disassembly of the pan. I recommend everyone carry a tube of this product in the glovebox; it will stop virtually any leak that is likely to occur if on a trip or in a remote area.
As I said, this stuff is NOT epoxy or JB Weld; once you break the bond you can pull it right off with your fingers. It's a perfectly sound solution to not only keep oil off the floor, but keep it from slinging all over the bottom of the car and ruining other rubber components until one is ready to tackle the entire repair.
You are right - do it right, do it once - when other front end components are sloppy enough to warrant dropping the subframe, the gasket will be replaced in the truly proper manner - with oil pan removed. The main reason I insist on dropping it completely is I'm not going to let my old gasket disintegrate into my oil pan with no room to properly clean it out.
BTW, I work as a Mechanical Design Engineer and pride myself on being absolutely fastidious with a very high attention to to detail. I can also appreciate a no-brainer fix when it's staring me in the face. I thoroughly cleaned the whole underside of the car last weekend during the subframe bushing/oil filter housing/vanos/inspection II service. Four days later completely sanitary under there