Mike-C:
The bare minimum a card will actually hold has to be 28 times 24 hours. If you’re doing 12 hour shifts (for example) it will hold 56 shifts (minimum).
That is not my understanding of how they work. I assume that you are working on the basis that each hour of use is being recorded separately which, in computer terms, is unnecessary (and wasteful of memory). All that needs to be recorded are activity changes. i.s. Stopping/starting, change of mode, etc. Hence for someone on Trunking/Tramping, RDC work, the card would fill up considerably slower than for someone on multi-drop.
And to answer an earlier question, in general, for Summary Offences, the ‘limitation of proceedings’ is six months. The most notable exception being Insurance offences where the limitation of proceedings is six months from the date of the discovery of the offence.