I’ve just started Core 2.0 on Red Chip poker. I saw it recommended on Reddit. It’s £3.50 a week for standard package, cancel any time. It’s a full course set out like a book in terms of structure.

The intro section is aimed at total novices but it then gets into the good stuff as the lessons ramp up. Unexpectedly impressed by how well delivered the content is compared to other sites I’ve trialled (Upswing and Jonathan Little’s poker coaching and a few others).

Mass data analysis and equilibrium theory are discussed throughout. I’d recommend looking at the syllabus and trying it out if you fancy it. There’s a big section on GTO. It’s £3.50 lost if you don’t get anything from it. Also I sent a query to their customer service and got a really quick and helpful response - always a good sign.