The best way to actually learn that is to actually just cook and read through the recipes and make tweaks as you go. The second best way is to find instructors/youtubers who understand this and convey it.

My favorite ice cream cookbook has like six recipes across 150 pages. It explains why those recipes work the way they do (milkfat percentages and cooking temperatures) and then it's just variations on the recipes in different flavors. I've broken like seven ice cream machines getting it right and it's been worth it.

Completely picking up what you're putting down regarding the dollar value and if I'm being honest was probably going to find an alternative way to access rather than purchase. Our libraries offer pretty much every book as ebooks on loan and for informational non fiction works you can usually glean the majority of the content through a quick peruse in-store or online synopsis.

Personally I do little baking but have been the primary cook in our household for the past 8 or so years and have been noticing that my dishes have been improving a lot lately due to noticing some ratios (particularly in pasta dishes, carbonara especially) that seem to work really well with what the family likes. These are probably rather personal and the missus does also somewhat despise that I generally never make the same thing twice cause I'm always tweaking things depending on available ingredients & whatnot, basically cooking from experience and feel. So I also agree with what you've mentioned around learning from doing and bringing in the look, feel & smell components to aid that learning.

The smell of things has made a huge difference in my cooking as well once I started to pay attention to when I could smell that things were done (mostly bbq and baking) - nothing more disappointing then following a recipe to the letter and coming out with an over cooked lamb shoulder (just one somewhat recent experience).

Why this was interesting was because I've realized that having a few ratios/rule of thumbs that relate not just to ingredient ratios but also to cooking times and styles I can be way more flexible and adventurous in my cooking while maintaining mostly consistent flavours and (more importantly) a happy family.

Also realizing the importance of trusting that you know your own appliances/cooking environment best has been helpful lately. Going back to the lamb shoulder comment, the recipe asked for me to have the grill at medium heat or about 150' Celsius for like an hour. For me to get my bbq up to 150' took a lot (it's a six burner, so lots of space) but I was determined to follow the recipe to the letter and instead what I did was I ruined the dish. Everything was telling me that it was too hot (dials were past mid way, fat flare ups, etc) but instead of trusting my instincts and adjusting to my conditions I just blindly followed the recipe.

So yeah, bit of a lengthy comment but love simple ratios like a 3:1 for a vinegarette and feel like I could definitely benefit from some more knowledge in that area to further bolster my cooking skills. I'll check out a couple of the youtubers you mentioned and go from there, cheers

I don’t know if it’s scammy - hard to tell without reading it - but it does sound really incomplete. There are so many variations on fats, liquids, liquids that are fats like oils, different behaviors of fats, the role of proteins like eggs, leavening agents… Maybe the book covers more, but just basic ratios doesn’t seem very helpful.