So you sound like somebody who wants to study strictly Isshinryu and learn everything you can about Isshinryu and not take up any other styles. So at least for you, when to take up a second style would be never. Is that the case?
Correct. And I feel that Isshinryu is not the be-all, end-all. It just happens to be what I study. If I had landed at a Gojuryu or a Shorinryu or a TKD place, then I'd be studying that.
The more layers of the onion I peel back, it seems there are more layers to investigate. I feel I'll never reach the end of the possibilities, the learning. It just goes on and on. So yes, I would not turn my back on that to try to absorb something else. I'd be worse at both, rather than better at one.