If you keep your queens for three or four years, you will find quite a few of them behave differently each season.
I've a three year old Amm that's never attempted to swarm, happy enough in a single brood but put her on Demarree this year for her genetics.
Another two four year old queens (sisters) one attempted on year one but nothing since and the other showed no signs until this season, when her usual eight frame brood nest expanded dramatically. Certainly not showing signs of slowing down.
Good combs of nicely drawn cells makes a difference, I've seen some double brood hives where if the rubbish frames with holes in, half eaten, parts of the foundation not drawn etc, were thrown away, the usable combs for laying would fit in a single.