You asked about the professional breeders - I bred rexes for about 5+ years. My females were bred once a year - you have to allow time to recover physically and emotionally. I was one of the lucky ones that my females did not come right back into heat after kittens were born. They usually waited 5-6 months before coming in again. Why? I have no clue, but it was nice and quiet.
The 3 week span is not the entire time they call or can breed- its usually a week of pre-heat, the actual week of being in full heat and the last a cooling off before they start all over, that's why I said about once a month.
The 3 week span is not the entire time they call or can breed- its usually a week of pre-heat, the actual week of being in full heat and the last a cooling off before they start all over, that's why I said about once a month.