No, I never did. I have worked and do work as an ESL tutor, so private one-on-one lessons. I've mainly done conversational ESL, so in that respect there's no book I need to follow. But I see your point: if I had to follow a lesson plan, I would look at existing books aimed for English teachers. I guess with these books in other languages, I've looked at it from the point of view of an autodidact.
taught ESL, sometimes teaching native speakers of up to seven different languages in the same class, and yes, this is exactly why the book needs to be entirely in the target language. In my experience, with a book entirely written in the language being studied, you also end up doing less "translating" in your head, thinking a bit more in the L2, which can be a plus.
For myself as a learner I also really like using books written entirely in the language I'm learning, with a couple caveats:
(1) I prefer to get at least a few "A0" basics down first before immersing myself in a monolingual text (which also means that at least the first chapter or two of a monolingual A1 text will ideally be review, which helps a lot - by the time I get into new material I've figured out the lesson format and the vocab they're using for instructions, etc.);
(2) it should of course be written by a professional who is familiar with language teaching, linguistics, textbook design.
But yeah, if you can find a text that is really meant to be used for teaching the language to immigrants within the country where the language is spoken, sometimes they can be fantastic resources. They often include a lot of cultural notes (which I personally like), often include very realistic scenarios and authentic reading/listening practice, they often include vocab that is overlooked in bilingual texts (more up-to-date, more slang, or more classroom and linguistics terminology). And on a personal note, I also like using monolingual books as a learner because it gives me a taste of how my students feel when they dive into our monolingual ESL text; it gives me a better idea of what to look for in the texts that we use and where they might need extra support if I've encountered the same types of issues in monolingual texts myself.
But of course, whether a monolingual text is "good" or not entirely depends on the quality of the text and the abilities of the author.