5-6 hours in a nappy is long enough if you want to stay fresh, longer overnight if you have the luxury of more than 6 hours sleep which is rare for me. So 28 minimum, preferably 35 a week would be enough for wets only. They are rarely on long enough to reach capacity or leak, i.e. the average number used is not so much related to absorbency or how much I wet, but my preferered maximum time between changes. After getting up I always shower and change immediately, have breakfast and then usually make a mess in the still-almost-dry nappy, requiring a second change. The next messy one is not so predictable, maybe after lunch or in the evening, sometimes both, but an extra one or two nappies a day is enough on average to deal with all the poo, making the total about 40-45 per week.