Is the info here reliable enough to use w/o question? I'll soon return to the darkroom after literally decades. It'll come back after a few screw ups but I'd like to keep the mistakes my own. What say ye?
Thanks.
I'd say they are a good starting point, and I have used them extensively because I seldom develop with the dilutions given in the film boxes. That said, you will have to figure out what you want to do with the film afterwards. The "ideal" densities are different for scanning vs enlarging, and again different for diffusion vs condenser enlargers. You can use a few thumb rules and get pretty close, though. Fortunately, it is possible to get decent prints out of slightly under- or over-developed negatives using contrast control and other techniques. It is also possible to modify the negative density up or down (usually irreversibly) with reducers or intensifiers, of which there are quite a few formulae. The latter always holds some risk, though, and if you want to do it with a precious negative, it is worth doing test runs with reference strips.
Given the above, the web times outside of manufacturers' data have the same reliability concerns, so always try to verify what the intended use of the publisher was. Most people develop for scanning, which is usually a less dense neg than for printing onto VC paper. The problem with scanning lies in the constraints on DMax, as I understand. It is sometimes really difficult to get a good scan out of an over-developed dense negative, because the light source simply does not give enough light, and the scanning time is what it is. It is not like in the darkroom where you can give more time for less light. At least that is how I interpret it. My solution has been to do multiple scans, sometimes as many as 16, and to blend them in Photoshop using Layers with blending set appropriately (have to go check my notes on that). It is not perfect, but it has saved a few images for me. Still, it is more work than I would like. So I try to split it halfway, so that I get relatively good scans and relatively good prints. That means developing ever so slightly shorter than most of the times on MDC or in the boxes. ALWAYS shoot test strips with every film/developer combo you want to use. Unless you are willing to accept just about anything in the results, standardise on as few developers and dilutions as possible. It is really hard to keep track of everything. I have settled on Rodinal and HC-110 as my developers, although I use TMax and occasionally caffenol too, but only with certain films. Rodinal is the cheapest, but tends to fog some films (Rollei RPX400, Kentmere 400), so for those I use HC-110.
Edit: I should also add that it will stand you in good stead to devote a bit of time and effort to shooting a few test rolls before you jump into photography per se. A good colour checker card with white to black gradations and a grey towel are two useful tools. My check works as follows: Take a mid-grey towel (the hue is not important), and photograph it at -5 to +5, with 1-stop increments, making notes as you go along. The reason for using a towel is that you need some detail to discern whether the film is recording detail or not. It is nearly impossible to tell when using a completely smooth surface. Then develop and see what you can extract when printing with your enlarger (or scanning, of course). If you can print the -5 (zone 0) as a black with barely visible details, and the +4 (zone 9) as a white with barely visible details, then you will be fine. The +5 is there to see if you are underexposing or underdeveloping. If it is not dense enough, you know where the problem lies. That is my method, but of course others may have a different way of doing things.