I agree with Ettina. It's just as needed. There are no set guidelines. If you are struggling with something that a therapist could help with, then definitely seek one out, but otherwise don't worry about it.
I wish I could find a good therapist where I'm living now to help me with some issues at work. I'd need to find someone experienced with NLD or ASD though, because they're NLD-related problems.
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Not all those who wander are lost... but I generally am.