I was wondering the same thing, yesterday I got a 1 day ban (at least 1 day as far as I can tell it's been over 24 hours now)
While refreshing the account status page one time it showed me some extra text above "Banned: Your account will be available again in less than 1 day, or earlier if you submit a successful offence appeal.". It said something along the lines of "your account is temp banned the next one will be permanent" which would suggest it's always a permaban after a temp but I havent seen the odd text since.
Does anyone know why I got a 1 day ban instead of 2? I have a theory of my own might be far fetched though. Clearly they didn't take all of my previous botting into account because for 5 months I've afk botted castle wars 9+ hours a day, last week I got 1-99 construction, 61 mining and 85 firemaking. On may 2nd I did 5-6 hours of smithing in varrock west and then 2 more hours of herblore at the GE, the herblore was at 2am EU time so it was past midnight in the UK as well. On my Offence info it says Offence date 03-May-1018, technically speaking the only botting I've done on may 3rd was the herblore.
Do we know how jagex reviews logs for flagged bot accounts before they ban them? Did the system catch me doing herblore and automatically send them the logs for only may 3rd in the ticket it made for my account? How many tiers are there to bans I know Bot Busting Moderate tends to be 2 days and macro major perma but I recon they split bot busting into 1 or 2 days depending on how many hours they caught you botting.