in a commercial rabbitry, fryers are shipped asap,[as feed conversion deteriorates rapidly after 8 weeks] the market is usually 4 to 6 lb, -with good breedstock, feed, and conditions this can usually be accomplished in 8 weeks, My grow-out pens were designed for early weening [rabbits weened a few days, or weeks before market day, or-to hold slow rabbits for a week or 3 until they were big enough to ship] or-- to hold potential breedstock until they were put in a breeder cage, sold, or shipped [culled].-- If I had 12 week old rabbits in a growout cage-- it was because there were extrordinary circumstances, or I was not keeping up with my work load. [or the buyer for the breedstock rabbits was late taking delivery]-- anyway-- it was rare that I had a pen full of large [10, or 12 week old rabbits.]At 12 weeks some bucks will start to breed,and fight, and and that is never a good thing. if the rabbits are sexed, and seperated, does can be housed together for a little while if you have to-- but-- I like to get does their own space ASAP after 12 weeks [even if it is a half cage, -I had a row of 18x24 cages for holding young breedstock] -- any way-- that was my program, and it worked for me---