Just today I was re-reading "Essential Darkroom Techniques" published in 1987 by Jonathan Eastland who according to the flysheet was a professional photographer with 18 years of darkroom experience and ran an international news and features agency. He too mentions the pinhole effect but qualifies it like PE by stating too strong an acid bath may( not will) create such an effect.

He goes on to say that he found that the very weak effect of development action from the use of a water bath seems to have the effect of enhancing shadow detail without increasing neg contrast. In this context he was talking about Kodak's HC110 which has a syrupy consistency even at working strength and a tendency to stick to the emulsion, hence its continued effect in the water bath. Unfortunately he doesn't expand on the correct water bath process for this effect so there's no way of knowing how long the film was in the water bath.

Interestingly Mr Eastland does not say he ever had a problem with a proper strength bath nor that he ever had a proplem with an over strength acid bath.

When books are written it is often the case that the authors reflect the then thinking and in the context of photography, the state of films then and maybe for a few years before.

PE. Could it have been the case that until some time in the 80s, films were more susceptible to pinholes that has been the case more recently? Hence the acid bath creating pinholes issue

I used to use an acid bath for film but more recently have switched to water. It's cheaper and easier. It seems to me that if the dev time has been something like 10 mins or even more and the tank is drained properly and immediately filled with say 250mls of water, swilled round and dumped in a matter of seconds then any effect of continued dev in what is a very dilute dev must be very small and effectively eliminated on the second fill and dump.

I normally use 4 fill and dumps before the fixer and haven't seen any difference in the negs compared to using an acid bath.