depends on the razor blade too i think....

i remember using the good ol' gillette necet razor blade and it almost never burns. can reuse it for a couple of times before i throw it away because its getting blunt.

the cheap razor blade usually what makes the razor burn

Agreed. I used to hate shaving. I used to shave only once a week on Sunday night because my face and neck would be red after shaving.

At the time I was using Mach 3 and normal supermarket shaving foam/gel.

Then I tried a DE razor and wow! No more burns! I even ditched the shaving foam/gel and only used hot water.

Im never going back to cartridge razors again. Single blade is so much better than 2/3/4/5 blades.

For me, razor burn occurs when I go over the same spot over and over and over.
Doesn't matter if the blade is sharp, blunt, cheap, expensive.

Previously,
If a blade was blunt, I would naturally go over the same spot numerous times to get a smoother shave resulting in razor burns.

Now,
If a blade is blunt and I don't have a replacement, I just go WTG once or twice and stop. Obviously not a close shave but no razor burns.