Did you do a lot of local recon in residency or was there another way you got to the point of feeling comfortable with those?
Looking at my case log, I coded 28 procedures for local flaps, 19 rhinoplasties, 4 PMMFs. We had a strong public hospital system, where I was able to take the reigns on a couple of these PMMFs, which happened to include internal lining reconstruction, including all the preop planning, intraop decisions, and seeing them in follow up in the clinic. Attendings were there at their whim or at your request.
We had private hospital rotations, also, where you are performing the will of the attending, so it is nice to have a mix to build confidence and know you are doing it correctly.
So, whether it is your first year(s) out in practice, or during your residency, you have to develop your self awareness and confidence with any procedure. There are inevitably unpredictable situations that come up, and part of it is gaining confidence that you can perform well in those situations to be safe and get the desired outcome.
I also believe that as a generalist, the various fields of ENT have cross-training benefits. The more types of things that are thrown at you, the more suited you are to deal with random problems. A few weeks ago, I used an ear drill to drill off the outer cortex of exposed bone to get to cancellous bone and apply a STSG for coverage (Moh's defect). Drilling mastoids, placing BAHAs, and doing bicoronal approaches for trauma all played in to me having no issue doing that, although I hadn't had that case come up since residency, and maybe once back then. Sure, I am not going to experience the same depth as a busy sub-specialist, but I'd argue the added breadth makes up for it and I can select my own cases rather than rely on referrals from other ENTs.
Ultimately, you are the best judge or yourself and your current abilities and you should decide on your own future goals and develop plans to get there. Once you assess what your needs are, you can do a fellowship for one of three reasons: 1) to build your skill and confidence, 2) the marketing benefits, 3) if you are going in to academia. If you don't need any of those things, a fellowship may not be necessary.
So, in other words "getting to the point of feeling comfortable with" {insert case} has always been a goal for me, and I have developed my practice incorporating that goal.