Hi, I have used a wide variety of epoxy adhesives and fillers over many years both as a hobbiest and as a professional marine engineer.
The cheap end products, from what are variously called dollar shops, pound shops or cheap as chips, etc. are usually fine for most non critical repairs around the home, and I usually keep some around.
At the other end of the scale, there is no substitute for the correctly formulated engineering products that are available, sure they are not cheap, but failure can be even more expensive. case in point, Many yeasr ago like about early 70's I used a Devcon product, don't remember which one, other than it was for high temperature, to repair a flame gouge out of a cylinder liner on a marine diesel engine.
The gouge was about 20mm wide and about 8mm deep in the top mating face of the liner where it mated with the cylinder head. The repair lasted about 3 weeks before we were able to get to a port where a more permanenet repair was available.
There are many specialist products out there, when it matters use them, they do work. when it's not important, cheap as chips is fine.