As a filipino my income for books reflects the formerly 6usd per day minimum wage back in 2010s and corresponding income - at this time I think I earned 600usd/mo as an IT Manager around the time I bought this book. I had to be really strategic in buying them and I had to accept that I will NOT KNOW SO MUCH. (note that because our incomes were small and technology goods were 2-3x more expensive cheap hobbies like TRPGs were how I got by).
When It came time to give away my books (moving out of my parents) i had to just keep electronic copies of these books.
As I'm reading OSR - I keep kicking my ass how frustrating it is to LEARN because they dont make sense. ONE OF THE SIMPLEST rules of thumb is just giving a KPH/MPH to types of Movement. I dont understand why they had to REMAKE the wheel by having all these different calculations - they just had to start with the basic assumption: Walking Speed is X. And then start BUILDING over that - marching, jogging, running, terrain, duration, etc...
even the Basic Logical foundations its an assumption I make as a Quality Management professional - Objective Based processes are its own Discipline (That's why Admin skills in TRPGs work differently in my experience. Even now when you look at my Role in our gaming group My analysis and Organization skills optimize the Options of the Players - you can even Go meta and Look at my Impact to the Gaming Groups options - what does a person with Admin Skill do? I AID the Players gaming rolls)
In the 1970s when this was written - the simplest way is to talk to a Soldier and ask what is their marching rate and base it off of that. Even around that time Small Wars manual and VEGITUS De Re military ( My copy with my notes)was available. from 4-6kph factoring terrain and people didn't travel straight lines - why is this all messed up?
When I went to Baguio was spend the afternoon interviewing the Horsemen who gave rides to tourists. Trying to confirm and disprove what I read in the books. Even with the Mountain Pony baseline, I can INFER race horses, draft horses, and mules, etc... In Mneme Variant Combat rules its possible to infer Bison and Fantastical mounts and close analogues. I was obssessed about one of the MOST UBIQUITOUS transports and tools in the era Horses which affected the Decision making of anyone travelling and the economics and constraints.
Whats funny is that when You learn that medieval people didn't have Visual Spatial Maps that - they had itineraries - list of places to encounter before they reached their destination - this means more data on walking and marching rates. Especially now with Google maps to review historical places.