I don’t honestly think you have to worry as much about slanting angles, etc… as much as you think. Certainly do whatever you are finding you have greater success with, but don’t think you have to change up you entire picking method for this.
The rhythm aspect of this is more a product of hand sync and accenting. It’s one of the more boring aspects of practicing anything, and guitar playing in general, but necessary all the same. For that you have have to slow down a bit, and work on developing that brain/ear/hand connection.
Like I said earlier, economy picking is naturally a mechanically faster technique from the get go like sweep picking is, meaning it’s relatively easy for beginners to get some incredible speed out of them, but most of the issues people tend to have with both are the more rudimentary elements and thus boring aspects of guitar playing such as rhythmic accuracy, synchronization and cleanliness while using them. To develop that, and really get good at them, you have to do all those boring things that people talk about.
I honestly feel that in the end, economy picking is most useful as a tool where you are combining it here and there briefly with other techniques. If I have time I’ll post another one of those licks in the show and tell that uses it on two strings to kind of get feet wet.