I have grown lettuce in almost ever unit I have owned (Sprout, Harvest, Extra, Ultra and Bounty). There are many members that grow using the Farm. They plant one side right away then about two weeks later start the other, This way as you trim on, then the next week you can clip from the opposite side. I do not own a Farm so can not verify for sure but if you scroll thru the different Members Gardens you will find those that do have farms growing lettuce.
For me I use a Ultra mostly and plant all 7 pods. After 4 weeks I give them a haircut for a nice salad. I will then let it grow more before trimming more. Me personally will harvest three times then I end it and restart. However, there are members that let it grow and grow and grow and after many months still have lettuce growing.
I know the above may not have answered your question but other may chime in for their experiences.
All greens plants eventually comes to an end. You can just stagger the planting in the machines you have..if you are big salad eaters like I am, you can just have 9 pod or Farms. I have the 7 and 9 pods machines and just plant one garden a few weeks after I plant the first. I don;t know about staggered planting as far as light getting to the smaller plants after the larger ones are spreading out..could be problematic.
But staggered machine sowing works for 1 big salad eater here.
My wife and I eat a large salad every day using the Costco spring mix. What Aerogarden(s) would we need to be able to grow our own on a continuous basis?
Daily? For a few days perhaps,, but it is not a bottomless supply. One has to wait weeks for the pods to regrow. I think even with a Bounty(don't be swayed by the name) and big salads you may get just a few days and then have to wait for a while.
The supply won't be any where near the Costco supply you are used to. You can supplement that, though with what you get from the AG.
IMHO the continuous(without a break) big harvests you are looking for would demand a few AG Farms in the house.
Perhaps you can pm some of the AG Farm owners here who have grown lettuce/greens and see what they suggest??!!