They work for a variety of reasons -
The room is temperature controlled.
The entire room has air circulation, a 52 inch ceiling fan running in reverse 24 hours a day and the air filter.
The room is humidity controlled with a programmable humidifier and each space/shelf has a constant but different level of humidity.
I maintain the lights and timers replacing bulbs and such as they reach their end of useful life.
By setting it up this way I can monitor and keep plants where they do best. For example the plants on the lowest level are cuttings and get the most humidity. The cacti on the North wall are placed much higher and get far less. The same placement applies for all in there. Doing this has resulted this year in 6 micro climates to work with, last year I had 5.
The lights provide enough light at 16 hours a day to keep them otherwise healthy. Using heavier HO T5 type lights does produce more growth BUT it is leggy and requires a lot of trimming. My goal is health not growing although they do anyways but it is not leggy growth with long internodes. When we have Bonsai again next year I will document each plant and share if requested.
It is a balancing act but once all setup and monitored for a week or so at different heights and positions does not need to be further adjusted.
I was going to add another 48 foot of similar shelving around the parameter of the room but it is not necessary this year. When I do the room won't need adjustments just monitoring of each level to determine best plants and placement, again for about a week. I figure over the next couple of years I can develop a stable up to perhaps 8 microclimate grow room.
Grimmy
