Here's a data point of why I am not freaking out about the smartctl data.
Yesterday around this time (45 minutes difference) I posted my smartctl data (2nd page of this thread) which showed a value of 70 for Power On Hours. Today, just minutes ago I polled the SMART data again...
SMART/Health Information (NVMe Log 0x02)
Critical Warning: 0x00
Temperature: 41 Celsius
Available Spare: 100%
Available Spare Threshold: 99%
Percentage Used: 0%
Data Units Read: 7,236,272 [3.70 TB]
Data Units Written: 3,414,729 [1.74 TB]
Host Read Commands: 115,870,648
Host Write Commands: 51,803,785
Controller Busy Time: 0
Power Cycles: 170
Power On Hours: 71
Unsafe Shutdowns: 3
Media and Data Integrity Errors: 0
Error Information Log Entries: 0
I use this Air for work and personal usage. Yesterday I was on this machine for 8 hours during work and then another 2 hours after. Yet the increment here is of a single hour.
Checking the meaning of power on hours (to make sure it isn't some dumb "you think it means this but it really means this), it is exactly what you think it should be.