'Straight razor shaving is not rocket science', is a white lie. The tools and techniques involved are far more primitive than a rocket, but the science aspect is one that is often mis-represented by those claiming to be at the forefront of research. In fact, the mechanics of straight razors are woefully under-researched. This has led to a number of popular myths and misconceptions, one of which shall be addressed in this article. More will follow.
"A 6/8 half hollow ground round point razor is the perfect tool for a beginner"
For someone new to straight razors, the variety of choices can be overwhelming. Razors come in different sizes: from 3/8 "moustache cleaners" to 8/8 "camping axes, and sometimes even less or more, respectively, at both ends of the spectrum. They also come in different grinds, from "singing" fully hollow grounds to "wedges" with no hollow grind at all. Add to that various points (ie the shape of the tip of the razor) and scale materials (from ebony to ivory via modern plastics), and you will see why many beginners struggle with the choice of their first razor.
However, there are no silver bullets in straight shaving. The human skin differs greatly from one person to another, as do manual dexterity, and personal preference. Personally, I started with two 4/8 razors by Heribert Wacker, a full hollow, and a 1/4 hollow. When a member of the Straight Razor Place helped me buy a number of other razors at very attractive prices, I soon realised that I personally get along better with 6/8 (or bigger) full hollows. I traded the 4/8 razors for 5/8 wedges, and life became interesting in another fashion. But eventually, I settled for 7/8 full hollows as my personal favourites. I do not mind 6/8 or 8/8 razors, but my alone-on-an-island razor would be a 7/8 straight point Henckels Friodur (stainless).
So coming back to the recommendation for 5-6/8 half hollow ground razors: There is some truth to it. They are readily available (and therefore usually cheap; they are relatively easy to strop and hone (but not easier than 7-8/8 razors); they offer a decent compromise between manoeuvrability and the ability to pick up lather (important if you do not want to interrupt your shaving to rinse or wipe the razor). But... as with any part of straight shaving, there is a learning curve that has to be mastered. Arguably, a 4/8 is more difficult for eg your cheeks or neck. But it is much easier to use around the chin, or the nose.
As for the grind, that is entirely down to personal preference. Funnily enough, full hollows are most often recommended by people honing for money. Indeed, honing a Dubl Duck is as much of a challenge as shooting fish in a barrel. With an elephant gun. At point blank range. These things are of German quality, but so thin that a few shoves across a hone will make them shaving sharp. Honing wedges can indeed be a lot of work, and typically requires significantly more experience. Not a lot of fun for the hobbyist, and not very lucrative for the professional. But if a beginner can get his hands on a shaving sharp wedge, I would highly recommend it. It will typically keep its edge longer, and allow for small errors during stropping. On a personal note, I would recommend a 5/8 spike point wedge - that should show you just how much of that recommendation is down to personal preference.
To sum this up: While not wrong, the recommendation for a 6/8 round point half hollow ground razor is misleading. There is a learning curve that has to be mastered irrespective of the width of the razor. While I would not recommend a 3/8 or an 8/8, anything in between will work for you. Because you have to acquire the necessary skills anyhow. Get one razor, stick with it, branch out once you have mastered this one tool.
