In my experience, both personally and as a mentor to a number of "jack of all trades", (1) is good practical advice for jr generalists. The OP appears to have

In my experience, both personally and as a mentor to a number of "jack of all trades", (1) is good practical advice for jr generalists. The OP appears to have significant experience already, and it does seem suboptimal to masquerade as a specialist in all job hunts, when that's not the real value you bring to the table. Its leaning on the third clause of the full text of the quote: "jack of all trades, master of none, but oftentimes better than a master of one"... in other words, become a stronger specialist at one thing than most of the specialists in that area. That's great, and some of us can do it, but we're still not as strong as a specialist of our strength. It means you always interview as if you're a couple weight classes below where you actually are. That's a practical compromise for a person starting out, but like the OP, with enough seniority, and the tremendous value that an experienced generalist provides, it feels bad to lean on that leg in all interview situations!