I am a diaper pragmatist. . .I like and believe in using them for their intended purpose as long as it offers some benefit. Putting on a diaper and immediately messing or using it offers no benefit, because I will just have to change soon anyway.
If I am going from underwear to diaper, I will try to use the toilet before putting the diaper on. If I am wearing a diaper and it is not yet at capacity, I will try to use it before I change. If I am wearing a diaper that is at capacity, I will take it off and use the toilet, then put on a new diaper- or underwear.
Whenever wearing a diaper, I pee whenever I get even the smallest urge to, which results in little spurts and never floods. The benefit I get should be obvious, I can go longer periods of time without being interrupted to use the bathroom and do not have to stress over holding it until I can get to a bathroom. ( For example, I never have to worry about when the next rest stop is when traveling and can get through 3 hour lectures at school without having to miss anything.)
I only ever mess when I know that I will be changing soon and will not be around other people until I can change. The only benefit I get from messing is not having to experience that butt clenching cramping I sometimes get. The smell and subsequent cleanup outweighs any other would-be benefits. ( True story, I was about 30 minutes from home when the cramps hit, I was driving. If I had not been wearing a diaper, I would have crapped myself or have been in agony for those entire 30 minutes. Luckily, I was wearing a diet and was able to just let it out and changed as soon as I got home.)