The grow is a self contained environment...more-or-less. While you don't need to spend every waking hour in the same room as your plants, it is important to understand what they are experiencing so that issues can be spotted and corrected as soon as possible. In an ideal scenario, real-time performance specs for the grow environment would be available to you anywhere and anytime...24/7. So while your lovely ladies may be in the dark, you never will.
Some environmental inputs, such as the plants' photo-period, can wreak havoc on your grow-show pretty quickly if the parameters fall too far out of alignment from the desired schedule.
So, for example, by logging and graphing the lux output of your various grow rooms, a simple glance is all that would be needed in order to ensure that the expected photo-period protocols are being followed in all the right places.
If you're looking to achieve maximum output from the legally-limited number of plants in your garden, you may also be taking advantage of advanced environmental control subsystems such as CO2 regulation.
With these more advanced grow environments, anytime you DON'T have to manually "break the seal" to check to see that things are in order...that is literally
money in the "smoke bank" that's being saved. This is because the leaking of light during a photo-period night or unnecessarily venting CO2, warmth, and even humidity will affect the productivity of your grow on a level that would be measurable over time...or at least from crop to crop. Installing telemetric equipment to facilitate the remote monitoring of atmospheric variables is a great way to ensure that all the important numbers are dialed into the appropriate operating tolerances...all of the time.