Two things or 3 really.

First off, sometimes cone locking nuts are ridiculously tight. Cone wrenches are too thin to apply much pressure on without distorting them. If you have one bike, OK. But if you have 50 or more, or work on a lot of bikes, you need something better.
Park cone wrenches are stamped steel .075 thick.
Thats 75 one thousandths of an inch.
Pick up a couple of metric wrenches, the 13mm and 15mm to start with, and polish them on a grinder until they are the right thickness. Don't let them get too hot. You do not want to risk softening the steel by overheating it. Only grind for a few seconds and then cool. Repeat.
My 13mm wrench is .110" thick and my 15mm wrench is .120" thick. You may still find that there are some few cones with a narrow land that is too flat for the wrench but not very many. Raleigh 3-speeds, perhaps.



Secondly: Grease in a grease gun stays cleaner than grease in a tub. To make lubrication easier, get a nozzle on your grease gun - something that can squirt grease into bike axel bearings with the cone being backed off only so far that the balls can neither fall out or become misaligned. Something long enough to reach through the BB to lubricate the BB bearings behind the sprockets from the left side of the bike when the movable cup is removed .




Thirdly: Pineapples.
Aren't these lovely ??
Size 4 at Costco.



Pineapples have a lot of roughage and will keep you regular.

Binky