I know a lot of different rabbit breeders have their own thoughts on a good breeding schedule for their barn. I've tried having litters year round, once a year, a few times a year, and only in the more temperate months.
Here's what I've found:
Does need to be bred more than once or twice a year or their litter sizes trend downward. This is not true of all does, but I've found it to be an accurate generality.
Older does, if healthy, can still be nice producers for you on a decent breeding schedule. Don't discount buying an older doe if she has exactly what you need to add to your herd. Many breeders will practically give an older doe away to make space for the younger generation. Don't assume the doe is wore out also- ask questions! Many hobby breeders never had their does on a rigorous schedule to begin with. You may be surprised at what an old gal like this can still do for your herd!
Does can hide their fat well! They may feel perfect across the ribs and hips, but be absolutely loaded with thick white fat on the inside. Gross, I know. But true! Does with huge dewlaps generally have a lot of internal fat, too. I know a
lot of senior doe show rabbits have large dewlaps and some people consider it a sign of glowing health, but I've noticed a
correlation in mine with reduced health. The evidence is apparent whenever butchering day rolls around and I haven't been vigilant.
It is better to feed more hay and encourage regular exercise than to rely on a complete pelleted diet and hope they move around enough. In thinning the ranks over the past two years, the lazy does that went berserk for pellets are the ones that either never got pregnant or it took multiple attempts before they would take. It is also less expensive to give your rabbits hay and cuttings from your property than to rely exclusively on pellets. Not to mention I wouldn't want to eat the same thing all day every day. Variety is the spice of life!
Breeding in the icy grip of winter or the humid heat of summer is a gamble for the doe and the kits. The heat and humidity is far more dangerous than the cold to the mother, but the reverse is generally true for the kits.
My preference is to breed more often and to limit the planned litters for the temperate times of the year, but I do plan litters through the heart of winter in some years as my rabbits are kept indoors. I don't mess with bad mothers and I do keep a 3-strike rule for all brood does.
Hope this is helpful. Please let me know if you have any questions or comments! :)