I used to breed commercially both for meat and the pet market .
The rest is to give the lactating doe time to adjust to the new role of mother .
If you constantly post partum mate her it will drag her vitality down by about the fifth litter . Though it can be worth while planning to do post partum mating if the doe is only into her third or fourth litter for certain events in the human yearwhen you can sell more pets /meat . like Easter , third / fourth week of the summer holidays , post crimbo week & the onset of the colder rabbit stew weather .
Most commercial breeders will cull the doe after 8 litters as that's when the fecundity drops off .
Mating just after her dropping the litter is a thing that happens all the time in nature , just like humans and for most mammals it is a time of very high fertility .
Having a doe in kit whilst she is with 14 day old plus kits is often practiced by commercial growers but you do have to be very observant of the stock for signs of stress.
If you're able to afford to be a bit laid back, giving the doe a complete 14 day rest after the kits are taken from her at 28 to 31 days is fairly productive for the big litter mothers to recover entirely .
I offer you a word of caution ..it applies to almost all of the creatures on earth .
Don't elect your breeding stock from the most prolific producing females . For some reason mother nature does not like it and the result a few generations down the line is a much weaker stock both in meat , FCR's and general health .
Perhaps it's natures way to prevent the species from over producing and starving when there is not enough feed available .
The best stock to select are from the mothers who have just one or two more than your average sized family ( keeping detailed records & a mating line log book helps tremendously ) .
My commercial breeding does were selected from third litters where the doe produced the second & third litters of 9 or 10 kits.
I used to buy in an unrelated couple of new 16 to 18 week old bucks every year and cull the old boys when they'd just attained three years old . The new bucks were not used till 19 weeks old because they were quarantined for a week in a separate quarantine building that was well away from the rabbit sheds.
The new virgin home produced does were usually mated to an older buck for the first mating at 20 to 22 week old , kept in separate cages for the last four weeks before mating to stop female to female orientation .
Much older and it often happened that the does were difficult to mate up & ended up being culled as meat for humans , raptor breeding programmes , reptiles or factory made pet food .