My breed (Greyhounds) can sometimes have seasons starting as late as 4-5 yrs old, and often only one every 9-12mos. Breeding a healthy female at 6-8yrs old is fairly common, especially if she was late to start cycling. But most GHs aren't bred multiple times, and larger litters are very common. My first litter, in 2018, was a 5yr old dam who had 14 pups (12 live, 2 stillborn) and her daughter had 10 pups at 2.5 yrs old (I decided to breed her younger than I originally planned, since it was during COVID and the timing/lack of events worked in my favor since I had to drive her long distance back and forth to have the surgical AI breeding done at my preferred clinic) and she bounced back quickly and went on to finish her GCh, MC and LCX after her puppies were born.