It's called building and maintaining a pipeline my friend, sometimes easier said then done but can be done. At one time I had 4 MB LBK's going, and later on up to 3 5 gallon carboys and a 6.5 primary. I now, by using better temp control and yeast management use mainly one fermenter and have pretty good turn around times, but I am going to secondary a Lager I have going now so I can brew again.
The waiting part, that's why I have three 3 gallon fermenters. With 2 or 3 fermenters you can stagger your brewing/bottling schedule so that you can brew batch every week or so and bottle a batch every week or so which makes the waiting seem not so long.
Yes with 2 or 3 you can be brewing and or bottling every week if you want to and can be drinking your own beer while doing it.
I'll shoot for that goal next winter. Would love to be bottling a couple gallons every Friday night for a couple months during the winter. I think that would get me a 12 month supply for sure.