Looks pretty good.
The 8 day vs 10 day Citi thing might just be because people count time differently. 10 days inclusive of app days is 8 days excluding app day. Said another way, if day 1 is date if first app and day 10 date of second app, that works out the same as if day 1 is the first day following app date and you apply after 8 days (which is day 9 counting this way or day 10 counting the other way.
Followed link to your blog and caught an error on your churn cards chart, Mercedes Plat fee is $475, not $450. Better bonus makes it better than the regular Plat at $450 fee.