Malcolm -
I'll be careful in speaking too generally as there may have been some variations in the early days in BD machines that I've never experienced, BUT, I am only aware of timers with 60-second and 120-second increments, and the vast majority of those are the 120-second design, especially in later models. I think the 60-second timer models were for BOL machines only with very limited cycles.
The most complicated of timers (typically those used in multi-cycle Lady Kenmores and the like) would be the candidates for higher second increments, but none of the Ladies from 1970 to the end of the belt-drives had greater than 120-second set-ups, not that I've ever heard of anyway. Some of these timers are very complex as compared to mid-line models, with two sets of switchbanks instead of one, many cam 'channels' and a lot going on in each cycle as there needs to be cams and switches to turn on an off detergent valves, to energize various solenoids, and etc.
I have always thought that the Enzyme Soak cycles, which in the early 1970s were 30 minutes in duration, were shortened to 22 minutes by the mid 70s in part to gain back four 'clicks' on the timer, which must have been needed elsewhere. The off positions on these timers were usually one only or two clicks wide (with the exception of non-suds timers that were OFF in what would otherwise be a suds return spot). The two Kenmores we had with Soak cycles don't have four clicks to spare anywhere on the dial.
Gordon
