Learned that lesson myself after a few messy jobs. A thicker paste doesn't slide around as much and dries more evenly. You're right, it makes the whole process way smoother.
I read in a DIY forum last year that a paste with less water sticks better to vertical surfaces. They said it reduces drips and helps with a cleaner finish. One user mentioned mixing it to a peanut butter consistency for best results. From what I've seen, that trick really does make things less messy. It also saves time on cleanup later.
Peanut butter consistency" is a wild thing to read in a DIY guide. I can't imagine spreading that on a wall without making a huge mess. It sounds like a recipe for clogged tools and sore arms to me.