Should I care what my HR max is?
If you have another (more useful) benchmark, then max HR doesn’t matter very much. The best reference is the aerobic threshold. Next best would be anaerobic. If you have either of those, then your max HR becomes a cocktail party metric similar to VO2 max.
If max HR is 177 and AnT HR is 172, then you have little to no room for improvement in terms of heart rate changes. That would put AnT HR at 97% of max which would be unusually high. However, if the highest heart rate you’ve seen wasn’t done in a max test, then I suspect your true maximum is higher.
It’s also worth noting that changes in threshold heart rates are “first wave” responses to training. Even after threshold heart rates have moved as far as they will go, threshold speeds can improve for years afterward. (For example, my max, AnT, and AnT heart rates haven’t changed in fourteen years, but my threshold speeds are much improved.)
So… if you’re curious what your true maximum is, get a VO2 max test done. If fitness is your main concern, then continue training the way you have been with most of your training time in Z1/2.