I was finally convinced, a few years back, not to wash my mouth out after brushing.
I brush after brekkie, to get rid of brekkie debris, Each time I use loo during night (two or three times usually), I rinse out my mouth, so probably not much acid build up.
In the evening, I clean my teeth when I get undressed (around 7 ish), only have water after that. If I leave my teeth until I go to bed, then I am tempted to 'snack' during those hours. Being lazy, once I have cleaned my teeth, do not wish to do so again, so know I cannot eat anything more. Has helped my weight reducing diet no end!!!!!