Might not be the most, but we did Fury and Lightning Rod on a whim in the same day. 1st ride on both...(Everything but Firehawk's twin in both parks- not enough Aspirin for that) Bailing on Holiday World the night before. Holiwood Nights, even.
Hm, I’ve done three parks in a day, but not with gigantic cred totals.
And the biggest cred parks in the States I’ve done in stages. I grew up going to SFMM every year, went to SFGAdv and CP eons ago when they didn’t have a lot of their current rides (though I think CP is probably my current record with 13).
Upcoming trips to KI and CW may break my record. The Jersey shore alone could do it, but I’m planning to do that in two days.