I would suggest there are different objectives in doing the conversions.
1) Obvious is to conserve the most $$. Using after tax $$ can save you taxes and maximize your account totals. See examples above.
2) Another is to minimize paying IRMAA for Medicare. This additional cost can go from $0 to $53, to $134, to $214 to $294 per month. It can also affect if you get help with ACA premiums and can affect how much of your SS is taxable.
3) One objective for me is to minimize taxes due on your kids inheritance.
4) One other is to allow flexibility from ROTH to take as much or as little as you want in any given year without impacting taxes. If you want to buy a boat, car, or house and need to use IRA money a ROTH will allow you to not be concerned with tax implications.
I'm sure others will have other objectives such as pay while you are in a lower tax rate but just to say it isn't always a clear choice. I would rather pay a known rate today and not have to worry about what rates will be in 5, 10 or 20 years.
YMMV