@Eugeny,
I got a problem to tell because I don't know how high I may go 
Maybe I should tell a good spec. I could tell endless application.
Having it like the PSG frequency register would be nice. It has 12bit counter and I think 1/16 of 3.57Mhz.
Even when actualy not high rates are used, you still want high granularity.
A prime example is playing variable duty waveform on the PSG.
And then there are endless similar cases, in music things are always interesting when they are a multiple or a fraction of the base tone.
Then, when one has this nice precision, solutions for all the beats per minute and midi keypress precision etc etc are included.
But there also is use for being able to count longer durations, a couple of seconds, e.g. beyond the disable interrupt zones of diskROM.
I don't know hardware but if one could get those 3 counters of 8253 combined to 24bit, that would be nice.
Also one can play digital samples and not have 100% cpu used but some left for something else.
Also all sorts of IO can be turned to pseudo-DMA with software. The main program runs like the hardware has DMA.
Did I already mention that the applications are endless
