The actual thread started because someone had a 40s GM car that had disc brakes attached to the original single pot master cylinder. I did indeed talk about the amount of fluid required to operate wheel cylinders compared to the amount of fluid required to operate disc brake calipers. The reality is, the master cylinder only needs enough reserve fluid capacity over the amount required to operate the brake system, to account for pad and shoe wear, and a bit of reserve. The stated concern was if the single pot master contained the amount of fluid required to stop the vehicle with disc brakes instead of the original drum. A comparison between the amount of fluid required to operate a pair of wheel cylinders and the amount of fluid required to operate a pair of disc brake calipers is relevant to this topic.

It is also very likely, the 40s GM brakes were not self adjusting. Seems i remember needing to adjust the brake shoes on nearly everything up to about the mid 60s. I don't believe the 11" drum brakes on my 1st 69 Road Runner had self adjusting brakes.

As for how often I check the fluid level in the master on my daily driver, the answer is, it gets checked at every oil change and before any longer then normal driving excursion, and gets topped off as needed.

Do you really not look at the fluid levels on your daily driver?
Gene