It's always good to have experience in more than one sub-vertical. At least have a feel for each of them to see what's going to come your way and be prepared for it. But you cannot split yourself into eight, nine or more areas, so definitley pick a few and then try to specialise in that. For example, Medical Devices... this comes in many different content types and doesn't have that much of a strict requirement, So it's always good to be able to work in Medical Devices and there is a lot of content in there. It's also good to have some experience in the software side for example as you may receive software localization from the Medical Device companies. So these fields link together well.

There is also the regulated side, Clinical Trials, Regulatory Labelling, this is a completely different story which might seem intimidating, but t's really valuable to be experienced in an area like that. These areas are very controlled and there is a lot to learn about, so which documents should you be referencing while translating? A translator equipped with this knowledge is very powerful.

So I would say try to limit it, but not just to one or two sub-verticals and don't just stick with Medical Devices. Always try to expand a little around that.