Originally Posted by
sweets
It very much depends on the age.
It used to be that sub 20,000 bph was the norm in the 50s and early 60s, then 21,600, and when people like Certina put 28,800 movements into their watches , they very much wanted to claim them as hi-beat, and they did so, putting 288 on the dial.
But at the same time, Zenith had already made the El Primero beating at 36,000, what we would now consider high beat.
It is a moot point as to how much more accurate a faster beat rate is. The theory is that a lighter faster balance is less affected by changes in orientation and accelerations. But it is interesting that now, in search of longer power reserves, some people are returning to slower speeds like 21,600 bph, having found that new hairspring technology allows for equal accuracy at lower speeds.