I think it's relevant, if it's a common "impression" that they sound different after some burn-in. And we won't know if that impression is common, unless people post things saying that's their impression.
However, I am reminded of the old joke, "Who are you going to believe ... me, or your eyes???"
Or in this case, "what are you going to believe ... a belief that burn-in usually isn't real, or your ears?"
Personally, although I'm skeptical, I think it's wise to "respect the burn-in." The phenomenon is either real, or not. (For any given kind of hardware.) If it's real, and you "finalize your impressions" at 10 hours, then your (initial) impressions may be off-base compared to the impressions that you would have made at say 200 hours. And if the sound changes, it could get better, or it could get worse. On the other hand, if there is no real burn-in phenom, but you patiently wait 200 hours anyway before serious listening ... then your impression is "right," but you (unnecessarily) delayed coming to that conclusion by 200 hrs of clock time. A possibly wrong mis-read on a moving target, vs (delayed but) always right ... easy choice IMO.