I hear that a lot, but I familiarized myself with it once and ever since it makes a lot of sense to me.
Source ending in “/“: You want what’s inside. Source not ending in “/“: You want the thing (i.e. directory itself). For the destination, it does not matter whether it ends in “/“ or not, but for consistency I like adding a “/“ anyway (I want to put thing inside the directory).
Source ending in “/“: You want what’s inside. Source not ending in “/“: You want the thing (i.e. directory itself). For the destination, it does not matter whether it ends in “/“ or not, but for consistency I like adding a “/“ anyway (I want to put thing inside the directory).