T-shaped is excellent advice but there is something to be said for “paint drip shaped” skills too: imagine a thick line of white paint on a wall and how it drips down unevenly. Some of the drips/skills are very long, some are short, and most of the paint is that wide beam.

In relation to the OP then, being a master of an area is valuable, but so is knowledge of a few others in some depth and a lot of other areas at a much shallower depth.