Ok, I’m with the white bread/miracle whip/bologna brigade. Except as an added filip, it has to sit for several hours at room temperature. This is how I grew up with it, as it sat in my locker at school, in my metal school bus lunchbox.
Occasionally (!) I will still do this — but I will make up the sandwich, pop it in a lunch bag and set it under a lamp for a few hours. Not quite the same, but you can’t go home again….