I would like to toss a quick idea into the arena on this.. the general teaching of setting up a 30 day autoresponder sequence is used in a bunch of training (mainly because it's friendly to newer marketers and it allows for some "set & forget" type marketing) but it's good to take it with a grain of salt and only use it as a guideline.
Every list is going to be somewhat different from the next, it does take a bit of testing to get a feel for the list, but once you do you will start to narrow in on what works best. If you want to only set up a sequence that's maybe a week long and then rely on broadcasts then that is totally cool too. It really comes down to your own style and how you develop it.
Just keep in mind that there are lists which you'll want to keep around and nurture very carefully to develop that solid relationship with, and then there are those types of lists which we may call "turn & burn" which is best suit for lists that you know is filled with subscribers which won't really keep opening your emails past a certain period of time for whatever reason. These types of list you want to hit them fast and hard, but not in a spammy way... it's not worth losing your autoresponder account over. These types of lists also tend to have a lot of new daily subscribers so if you're not meeting that criteria then it's not worth even considering because the "turn and burn" method of marketing will get you a lot of unsubscribers very quickly, as well as a fair bit of complaints, even if you're not necessarily doing anything unethical... it's just the nature of things. So long as you stay under the threshold which is indicated in each autoresponder.... they all have a "complaint counter" then you'll be just fine. (stay out of the red, basically) which will vary based on the size of your list but typically you want to stay under 0.02% complaints.