He didn't say, it was quite broad comments about the poor temperature control, he would have had no idea of what the actual temperature variations were. However, it's more typically when there's a sudden drop, causing the emulsion to shrink, and it affects the gelatin super coating first.~
The issue with using running water here in the UK is what's sat in the pipes in a house/darkroom can be quite a few degrees warmer initially, and then a sudden drop as fresh water at ground temperature comes through.
When I'm in Turkey I work at the tap water temperature which is very consistent, aside from around 6 weeks tin the Winter it's a consistent 26/27°C in fact I can keep the entire cycle developer to wash within +/- 0.2°C. I use a digital thermometer, however I'm not obsessive about that /- 0.2°C, it's purely an observation, the ambient temperatures there are 100% in my favour, temperatures stays stable
Ian