Well, situations vary. As a hospital RN, I have been involved in two lawsuits. I was named in one of them as a co-defendant. Neither of them amounted to anything but the experience was essentially the same both times: while I'm sure the hospital would have loved to throw me under the bus, they couldn't. Their attorneys could not defend themselves without also defending me. And both times I came away clean. No black marks on my record; none of my cash expended.
Did I have professional liability insurance? Not a dime's worth of it. It made me a very unattractive target even for a nuisance suit as you can't get blood out of a rock.
My attitude would be very different today as I have a home that's paid for that I wouldn't want to lose. But at the time, I rented my apartment, my car was 6 years old, and there was nothing I had that they wanted.
So I guess the test I would apply to answering the question would be: do you have anything worth taking? If you do, spend the money. If you don't....