Tweaking: I have seen a number of veterans say that same thing— they do length first, girth second but they are not sure whether they believe the theory.
In other words, they do length first, girth second ‘just in case’ (exactly what you just said).
Light To Moderate Girth Work OK
I think light to moderate girth work wont hinder length gains, especially if a guy is sub 5” MSEG. However, it depends on the routine. I find anything related to girth is completely counter-productive for hangers, although at least one guy claimed big gains with jelqing + hanging (I read on this guy at MOS, dashdemig or something if you want to look him up). However, I found his story a bit hard to believe, as he claimed 3.5” in just 15 months and he supposedly used up to 600 dry jelqs per day. So, I didn’t quite find his story believable, so now I am thinking maybe I shouldn’t have brought this up…
Back on track though, manual length & girth work seems to work great (e.g. jelqing + stretching). So in this sense, length & girth work together can actually be helpful. Keep in mind once again, this is with light to moderate force—at least this is my observation.
Advanced Girth Work (Might be Counterproductive)
Ok, back to my point… only advanced girth exercises seem to hinder length gains: clamping, horse440s, erect bends, ulis, etc. should be avoided until you reach the point where you really need these to continue making gains, just in case.
My point: based on my observations, it appears light to moderate girth work doesn’t seem to prevent or hinder length gains.
Question
I do have one question though: do guys that start with really thick girth (6”+) ever report trouble gaining length? If they do, that’s anecdotal evidence that just being thicker can hinder length gains. I have seen veterans say anecdotal evidence suggests that guys with skinny dicks seem to have an easier time making good length progress.