The first huge benefit is that it forces me to consider the whole unit when planning, not just focusing on lessons. There has been a lot of talk recently about the lesson being the wrong unit of time to plan for, but when our time is split in that way, I find it difficult to not plan in those chunks. Using booklets has helped me break through that barrier.
Putting the booklets together in the first place takes a long time. But now I have a set of booklets on 21 units covering the IGCSE, and I can reuse them again and again. In reality, I make adjustments each year, but the bulk of the work is done. In future I can plan a whole unit in about an hour as I just need to review the notes I made the last time I taught it, and make the necessary changes.
When planning lesson to lesson I always found that my focus was on the current bit of new learning, and rarely did I think about interleaving other topics in. But with a bigger picture of planning, I can add more interleaved exercises within the booklet.
As everything is in the booklet and the booklet is printed for the start of the unit, there is no need to be running trying to get the worksheet copied just before the lesson. It is also cheaper on photocopying as I am not copying things that I end up not using, and there is little wasted white space within the booklet. Three separate worksheets might fit on a single double sided page, instead of 3 single sided sheets.
In the run up to a particular skill, I no longer have to spend time finding/putting together a lesson/activity to use. I can focus my attention on thinking about how I will explain difficult concepts clearly, what visualisations I could use to enhance my explanations, and any other materials that might enhance the teaching of that particular skill.
Perhaps not groundbreaking, but I can't forget to teach something. It is all there and in my face. I can't get to the end of the booklet without teaching everything from it. Of course, I could forget to include something in the booklet, though that is less likely. What does happen is that I realise I need to break a skill into more smaller bits, but I can just take a note in my copy of the booklet to refer to later.
And on that note, whilst teaching I can easily annotate my copy of the booklet. This means I can note anything that doesn't work, or works particularly well, as a reminder for next year. As some of my colleagues are also using the booklets, my hope is that they will start making suggestions too and the booklets will continue to improve each time they are used. No need to reinvent the wheel each year.
With everything in the booklet it is easy to navigate as I just say the page number they need to turn to. No getting out different books, or finding the ebook. For most things they don't even need their exercise book as they can write straight in the booklet. This saves maybe 3-5 minutes every lesson, which over a few weeks really adds up.
In Teach Like a Champion 2.0, Doug Lemov discusses the strategy he calls Standardize the Format. The idea is that I can save time and effort checking student work if they all answer in the same format. Booklets are perfect for this as they guarantee that all students will write in the same space. Walking around the classroom you can quickly look to see every response, as they are all in the same space, so you don't need to hunt for them.
My students have been particularly happy with the booklets in the run up to exams. The booklet gives them a structure to their notes, clearly shows examples, and has plenty of practice questions for them to do. I provide an electronic blank version of the booklet too, so some students use this in their revision, printing it off and filling in the examples and your turns again. What a great way for them to practise the skills they need.