Of course, us OG types, fitting things into small spaces, were the root of Y2K. We program bit by bit and try to save bits wherever possible. With the current space on drives and in memory, and "aligning" data in the same chunks as the processor, saving bits is a lost art since most do not have that "saving" mentality.
For grins, I store dates as a number offset (4 bytes), so there is and was no issue, at least not for about 12 million years from 12/30/1899. Even simple on/off flags are now usually 4 or even 8 bytes (instead of one bit) because of being better aligned with the processor, although the OG in me still uses bit "flags" where one 8 byte item can have 64 different on/off bits. I cannot waste bits! The one exception is stored data. After many years of having to update record structures when adding things, I built in spares many years ago (which were initialized too, so I know what the value is). For the most part, the record size aligns nicely with drive storage chunks, or for smaller records, is some sort of easy to test number, like 200, 500, 2048, etc.