Can you use average outstanding mortgage principal over course of year if paid down significant amount early in year bringing balance below 750k cuttoff for deduction?

For example, if outstanding mortgage = $1MM on January 1st, 2020 and interest = $20k during year, you could only deduct ~3/4 of it. However, if you paid down -$500k of that mortgage on January 15th, the vast majority of interest you paid through year was below the 750k cutoff, yet striking the balance as of January 1st wouldn't adjust for that.