My commuter has horizontal drop outs that look like the one pictured below with axle nuts holding the wheel in:


One time I ran over a big nail and bought a new tire and tube at the closest shop, fixed it up but then ended up leaving the bike there to true the rear wheel as I noticed it wobbled bad. I have a little stubby 15mm box wrench in my small seat bag, and when I was removing the wheel recently, the drive side nut took a LOT of force to untighten. Have I not been tightening it enough in the past, or did the bike mech just end up torquing it like crazy that one time? Is it necessary to gorilla it down or "just tight" with the stubby wrench enough?

I tried to search and google this but must be using the wrong search terms... thanks in advance!