Let’s say I’m a certain Senatorial Publius running for Consul in the years after the Sullan reforms, which (among other things if I’m remembering the time and what was intended to happen) were supposed to prevent people from accruing consecutive consulships/posts by placing a requirement for a certain number of years to wait before even trying for that post again.
I win my office and I’ll be Consul from January 1st 75 BC, until December 31st 75 BC. In this case, would I be able to achieve the consulship of January 1st-December 31st of 65 BC, or would I only be able to serve in the 64 BC consulship? Was that clock/restriction to have started at the moment the new year starts on the 1st of January 74 BC, thereby giving me 11 years between the start of the 75 BC consulship and the start 64 BC consulship? Or 10 years including the year of my first consulship in 75 BC?
I know that a lot of Roman law could be vague, but I’m very curious as to how this was interpreted by them. By Neptune’s beard I want my next consulship to be earlier damn it!
I mean, the major problem here is that we don't really know so much about what was supposed to happen as what actually happened. Roman laws weren't really laws, but suggestions. This is especially true when we get to talking about term limits. Romans played with those all the time. Here is a list of Roman consuls. You can see how many of them served twice within ten years, although this did become less common in the late republic.
But if you really want to think about the 10 year rule, it might help to think that Romans counted inclusively and that the two consulships (or maybe the two elections? who knows) needed to be separated by a 10 year interval. So 64 BC at the earliest, 63 BC if we're talking about the elections.