This is the IRS link you were referring to - https://www.irs.gov/payments/frequency-limit-table-by-type-of-tax-payment
The discussion branched out in this thread. Only two payments can be made per year for taxes due on a Form 1040, etc. as noted in the table.
However, using the IRS payments website you can make 2 payments per day using Direct Pay regardless of where the payment is being applied. So in theory you could make two payments using Direct Pay for taxes owed on a Form 1040 in one day. But that would be the maximum number of payments as noted on the Table for a form 1040.
