This is absolutely incorrect. You cannot make a lump sum payment at the end of the year without being subject to a 2210 underpayment penalty (2210 is the form used to calculate the underpayment penalty). The government wants their money in roughly even payments throughout the year, either in withholding or 4 equal quarterly estimates.
To avoid the 2210 penalty, you must:
1 - Pay 90% of the total tax due OR 110% of the prior year's tax bill
2 - AND make your payments through withholding or equal quarterly estimates (a payment with your return by Apr 15th is considered a Q4 estimated payment)
Paying nothing during the year and paying it all with the return will owe a penalty. If you aren't paying the penalty, you aren't calculating the 2210 correctly and haven't gotten caught.
My income varies throughout the year, and tends to go up at the end. I've gotten hit with penalties in years when Q4 was better than expected and results in a higher than expected tax bill. Yes, I'm supposed to know in Q1 how much I'm going to owe at the end of the year and pay it in Q1. You can't say "Well, I made a lot in Q4, so I'll pay it in Q4" - you were supposed to know that was coming (even if you can't predict) and pay for the Q4 income in Q1, Q2, Q3, and Q4.
Correct, changing you withholding does not change whether or not you get to take the credit, but it does essentially change when you can take the credit. Don't change your withholding and you get the credit in one lump sum next April. Decrease you withholding, and you get to take the credit now through the end of the year in smaller increases in your net pay.