15 seconds seems ridiculously short to me, though I can't argue with someone who says "works for me" in their particular situation. OTOH, film doesn't have the moisture content of, say, a chunk of steak and doesn't have to "thaw" in the same way. My rule of thumb has always been to be sure any visible condensation is gone and the film cartridge (for 35mm) or paper and spool (for 120) doesn't feel cooler than ambient. This will take longer than 15 seconds for most of us, but not hours either. Probably more like 15 minutes depending on ambient temperature and humidity.

For 4x5 I do wait longer because it's always wrapped inside the box. So far I've not had any problems with it either but the preparation I use for loading holders pretty much ensures I have to plan time for it anyway so film warming is just included - typically I take the film out earlier in the day when I plan to load holders that night.