I try to write software such that it would work for a time traveler (who takes the computer running the software with them) as much as possible. That is, distinguish between elapsed time within the system, which is monotonically increasing, vs. calendar time and time of day, which might go back and forth arbitrarily and is just a label. This isn’t always possible, for example with regard to external last-modified times, but designing with that distinction in mind tends to make systems more robust.