You just keep cycling new plants in, every so often, you figure out how often it takes to flower and you want to veg for and you start adding plants every XX weeks, So if you want to crop out 4 plants a month, you would want to make sure when your flower'd plants are done that you have some you have already going in veg to replace them you can't get the timing down perfect but you can get a week give or take once you get the hang of things, the more plants you do the harder it's going to be and the more room your going to need, like I plan on cropping out 10 every month, so I want to have 10-15(incase some die or you have issues with them) going from veg to flower room when they are done, and clones or seeds ready to start putting in the veg room, kinda gets a little confusing but once I get it going It shouldn't be too hard, it just doesn't work out when a plant you have flowering is supposed to be done in 8 weeks but takes 10 now your veg plants are going an extra 2 weeks which could cause problems if you don't have room, but them are just some of the factors you can come into play or to be safe, always make sure you give it an extra 1-2 weeks time to flower incase it ever does go longer, so there is a 1-2 week gap you have going in the veg-flower room, plus you have to also dry, and trim it so remember your going always make sure you got time to do that and lots of space to dry, hang and cure if you plan to have quite a few going.