... and now the depth limit seems to have disappeared. Maybe it's a time restriction.
I forgot to mention that people also get noncompete mixed up with nonsolicitation. You can't hire me as a framing carpenter in California and try to demand an agreement that I not work as a framing carpenter for another contractor, or even that I not start my own company. But you can require that I not use relationships I built with your customers when I was your employee to convert them into my customers. And obviously there can be grey areas there.
For "Valley" purposes, that usually only affected people in sales, though.
... and you can NDA me and say I can't use your secret hammer grip. You just can't completely stop me from competing with you if that meaningfully restricts my ability to do the kind of work I know how to do.