Some books on Irish have lessons and don't teach any grammar, with the idea that grammar is extremely complicated, and that it's best to just teach with examples and let the grammar kind of go in by osmosis.
This is not that book! It has lessons and examples, but it will break down the lists of things like conjugations, for example, and explain grammar!
I had already memorized conjugations of French verbs, so for me it was not a big step to memorize lists of prepositional pronouns because they are like times tables, you will need them so you might as well memorize them.