To elaborate, the first thing you do when researching a new film is go to the tech sheet and look at the
characteristic curve. That will tell you a lot. For instance, most Ilford films have a moderate toe to them, so that would inform me that in harsh lighting, I might in fact want to begin testing at half box
speed and work my way up (depending on my developer, of course). But with T-Max films, the toe is
much steeper, so I might start at actual advertised speed. With a true old-school 200 speed color separation films (most of which are discontinued), the toe retains contrast way down. Some films just
dont like overexposure of you'll push yourself off the cliff at the top, and blow out the highlights (that
is, if you want to maintain good midtone gradation). Then if you look at the curve for something like
Pan F, you'll see you don't have much wiggle end at either end of the curve, so maybe not the best
choice for harsh lighting at all. Once having made these generic distinction, you just have to test and
actually print until you understand a particular film's specific personality and pros and cons. Small camera users tend to have less choice because the priority is often upon fine grain, at potential sacrifice to tonality.