Yes, the headings say 5 months for 2nd quarter and 8 months for 3rd quarter, so the pre-filled percentages for the 2nd quarter numbers should be based on 5 months and the 3rd quarter numbers on 8 months.
But the pre-filled percentage calculation on line 20 is therefore wrong. 5 out of 12 months (for Quarter 2) is 41.7%; when you take 90% of that, you get 37.5%. That's what the pre-filled number on line 20 for quarter 2 should be. But they filled in 45% instead, which makes the amount of estimated tax for the 2nd quarter too high. Same issue for quarter 3. Quarters 1 and 4 are correct.
