I'm going to offer something of a dissenting view here....
The most important thing is being happy when you pull your knife out to use it. That's the single criteria, really, imo.
I've grown leery of pretty much all technical justifications of any sort of equipment, from camping gear to ski gear to cycling gear to knives. IMO, 99% of discussions are technical arguments that we slather over and on top of personal preferences. If you like something, no matter why you like it, you can find some technical justification for it. Might as well just stick with, "It makes me happy."
To answer your question, yes, back in the day, different blades had different uses. Main blades sort of speak for themselves.
The smaller "pen" blade is the most common 2nd blade and as the name implies, it started off for cutting quills to write with. Survived as an all purpose small blade for smaller cutting. If you work with wood at all, it shows its use pretty quick.
Other blades had even more specific uses. Sheepfoot blades were used to work on sheep hoves. Also popular on boats as they lacked a sharp point and could be used on a heaving deck with less change of stabbing somebody. Spey blades were for speying cattle. Awls were for repairing leather rigging. If you are a sheep herder, a cattleman or if you regularly use leather rigging, these shapes may have work related value to you. (ahem)
On the other hand, it can be argued that multiblade traditionals have "earned their keep" over many decades for good reasons that long go beyond their original uses. Lots of folks find they like having 2 or more blades.
Or, it could be you get bitten by the history of the knives. Regardless of their utility, there's something about a design from back in the day. If that makes you happy, that's enough.
Lastly, plenty of traditional knives were single blade designs. Nothing wrong with sticking with one either. I prefer a pocket knife that can double as a table/steak/food knife. But that's just me. I'm not you. The only way to tell is to try them out.
edc-pair by
Pinnah, on Flickr