Workout zones

Hello
Looking for advice from knowledge users.
I am 40 years old man and using mainly crosstrainer/eliptical for my exercises.
I have calculated my approx max heart rate to be 180 and also this is in line with my Garmin watch which seems to calculate heart rates same way.
I am exercising between 3 to 5 days week for 50min .
During the exercise I am following this pattern:
1.5min warm up - slow (below up to 120bpm)
2.5min faster(between 120-135bpm)
3.30sec max followed by 4.30sec hard (first 30sec unable to measure with my watch then between 150-160bpm)
4.5min slowing down until heart rate drops below 140
5.Repeating steps 3 and 4 another 3 times so during the training got 4 rounds all together.
6.5-10min cool down slowly dropping intensity until heart rate drop to or below 120.

I have set my eliptical to max settings so it is at harder configuration as it can.
Please advise if above pattern is safe/ good to follow?
I have also attached screenshot from my typical training. Plot.

Also would like to know how often VO2max is updated as mine seems to be every month ?

How does VO2max works on Vivoactive 4 ?