Without commenting on specific cases and if I understand your question properly, there could be a number of reasons.
First off, each jurisdiction has its own rules as to how quickly a Mason can advance. At least one allows (or did allow recently) all three degrees to be done in one day. (IMHO, that’s not a good idea, but it’s hardly my call.)
Secondly, one lodge might have a lot of candidates to put through. When I took over as WM of my lodge, for instance, I had not less than 16 EAs and FCc awaiting advancement. Given that there is a limit on how many candidates can be put through in one meeting, more people means more delay. Turning this around, if a given lodge has but one man wishing to become a Mason, he could be initiated, passsed and raised to the rank of MM as quickly as his jurisdiction’s rules permit (in my jurisdiction, for instance, not much more than two months - initiation, wait 30 days, passing, wait another 30 days, raising).
Third, in most places, it is up to the Worshipful Master to decide when a given candidate is ready. In my lodge, for instance, we require a junior Mason progress through some formal training before he can advance. A Mason belonging to a lodge without that requirement would find it easier to progress quickly.
Fourth, the individual’s schedule must be considered. If his shift hours change, for instance, that might pose a problem to quick advancement.
There are no doubt other factors, but that’s a start. Advice is always worth no more than you pay for it, but here’s mine anyway. Don’t be in too much of a rush to progress. There’s so much to see, to much to learn, so much to appreciate at each level and he who measures success merely by speed risks missing a lot of valuable, enjoyable things.
Welcome to the Craft, my brother. I sincerely wish I could be in your shoes, just to have the pleasure of doing it all over again.