[Answer]

2020 - 1994 = 26 years

365 days x 26 years = 9490 days

To your first point, Corleone is a former member of the wutang clan and the original frontman of Linkin Park, he does not take days off.

So that's still 9490 days

Lets ignore the leap days, as you insisted

That's still 9490 days

AOL chat was popping until about 2004. So that's 1994 - 2004, 10 years. 10 x 365 = 3650 days

Meaning for 3,650 of those days, your boy corleone was flexing hard on AOL Chat rooms, and keep in mind he was in his prime dropping far more bars on average than he drops now

If you were around back in AOL Chat days, you know we did like 5+ keystyle battles a day. We didn't do this weak ass i need 14 days to write a verse and then im gonna ask for an extension bullshit yall do these days. We showed up, dropped bars on the spot in 10 minutes and moved onto the next battle. You could easily do 20 battles in a single day if you really wanted to.

So let's lowball it and say Corleone was doing anywhere between 4 to 6 aol keystyle battles a day for those 3650 days. Averaging (4+6 / 2) = 5 battles on average

So let's just say on average he was doing 5 keystyle battles a day on AOL Chat between 1994 - 2004.

obviously he won every battle, otherwise his record wouldn't be 20,000 - 0.

That's 5 keystyle battles a day for 3650 days, which is 18,250 battles total.

We still have 5840 days left to account for 2004 - 2020 (that's about 834 weeks)

If he only battled 6 times a week and rested on sunday the way any God of text battling would do, that's 6 x 834 = 5,004 battles.

If we add those 5,004 battles to the 18,250 battles corleone completed between 94 and '04, he not only would've been ABLE to battle 20,000 times, it is actually highly likely that corleone's real record is somewhere around 23254 - 0

So we can see that if anything, Corleone was being modest about his record