The Total Time logged in is probably a non-tweekable SMF feature. I found this thread where someone inquired as to the specifics of its calculus on SMF:
https://www.simplemachines.org/community/index.php?topic=496342.0Aparently:
OK, first thing to understand: the entire concept of a 'session' in SMF terms, like any other online activity, pretty much meaningless.
You are not 'constantly logged in'. Ever. Not even if you select 'forever'. That's mostly a convenience for SMF to remember you rather than having to reauthenticate every hour/day/week/whatever.
It is not, in fact, possible to be 'constantly logged in' in a conventional web based setup, because HTTP doesn't understand the very idea of 'logged in sessions', not at all.
You click a link, in HTTP terms, this is a single request. As far as HTTP - the underlying transport method for the internet - is concerned, the next time you click a link, it's actually irrelevant to the previous one. It doesn't know any different.
What happens, then, is your browser - on your behalf - is sending the details to prove you are who you say you are, by saying 'hey, when I logged in, you gave me this code, here it is again, you know it's me, right?'
What happens is, when you revisit, this same code is provided. SMF reauthenticates you and boom, you're logged back in.
Except that this happens *every single page*. SMF has no way to know whether you're still online reading or not. Right now, you're marked as online, despite (at the time of posting) you made this thread 15 minutes ago. So even though you could have closed your browser and disappeared for the day, you're still online.
As a result of that, SMF has no real way to calculate when you are or are not online, and makes a guess based on when it receives the reauthentication codes, making an allowance based on too long between visits or not long enough between visits.
The result is that it is *never* going to be correct, it is always going to under-report by a certain factor, and that it basically isn't fixable without redesigning the core of the internet as a whole (though you can sort of cover it by redesigning SMF as a whole to enforce a constant connection, if your server could handle it, pretty much all of them couldn't)
And no amount of session juggling is going to change any of that.
<…> a user who makes more requests over a given period of time will see their online time increase more than a user who makes less requests over the same period of time.
It is an approximation of time spent online, nothing more.
If I’ve read it correctly, those accounts are very possibly constant scrapers (or constant something or other), querying the forum. The algorithm, which is not described in the above quotes, may be adding-up many petitions from multiple sessions on the same account, rendering those extremely incongruent numbers.
For example, My scarper Alt account has a logged-in time of 54 days. The account has been active for just over a year, and is active around 12 hours a week from two different simultaneous sessions. 1 Session over a year would add up 26 days roughly (12h*50 weeks/24h), so 2 sessions querying at the same rate would add up to 52 days (that is my 54 days, give or take).
If we take the first account from the list (@btcnfan), that account has been active for 491 days (give or take). The total Logging time for that account in that period is 4909 days. That could mean that the account has been actively querying the forum for those 491 days from 10 different sessions.
This is all conjecture though, but the forum sure knows if they are bot-type-1-query-per-second-multiple-session type accounts.