The original question asks how many we can, or do, 'fill' in 24 hours. That would be a couple of Betterdry or 3 - 4 Tena Active Fit Ultima. As I rarely wear a nappy until it is saturated or at risk of leaking, and I use my nappy for bowel movements too, the number actually used is greater, often five or six. Days with fewer wets or limited changing opportunities, it might be only four. On very wet days, or ones where I've had multiple early changes as a precaution against being stuck without changing facilities later, up to seven. Another factor is the timing of bowel movements relative to wet changes. If I have a messy nappy soon after changing, as is usual in the morning, I have to change again; if that happens twice in a day, it bumps up the number of nappies used.
With continuous wear, skin care is very important. It seems that I change more often than average, but the reward is almost complete freedom from any skin irritation or rash, without need of creams or powders. I'm not exposed to ammonia because the nappy is never on long enough for that to build up. It also means I never smell wet, I only have to worry about smells when I make a mess.