I think it depends on how much you like the pattern and the fabrics. I enrolled in several BOMs of the years and did nothing with them. I ended up selling them for way less than the cost of the fabric. But I have some other BOMs that I have half finished (was working full-time - retired, so now I need to finish them
).
As someone mentioned earlier in the thread, check your LQS to see if they do a BOM where you buy in for the first month, then complete blocks to bring in the following month for a free block. I did complete a couple from my old LQS that are this type and enjoyed as well as currently finishing one up (ends this month) at my LQS, where they are doing flowers and baskets, you could choose or the other, for I believe it was $10 signup, or a third option was both, where you do one set as the finish and get one free, still the $10 signup for the one, and the second set is $60 up front to pay for the whole year. I get two patterns (one flower, one basket) and fabric each month since I signed up for both flowers and baskets. My only thing was I am not crazy about their fabrics, so I am using my fabric stash to make them my way. These type of BOM may not always include the background fabric for the block, but that helps make it more personalized since you choose the background fabric. It's fun to see how different they look.
Having worked in a LQS, the BOMs like CW involve the store enrolling with the mfr who provides the patterns (both for the shop and the customers), ordering the specific fabrics, cutting the fabric pieces per pattern directions (they actually include the amount of each fabric for each month or quarter the shop is to provide for the BOM), packaging the BOM, making sure each customer gets their BOM, and shipping them out. Depending on how many customers are in the BOM or how many different BOMs they have, the shop can have several people dedicated to just processing BOMs .