The point is that strawhat improve during the 2months, Robin train to get haki, Chopper can now use 30min monsterpoint.
Nami get zeus but here Oda clearly show both Nami and Usopp where not capable to beat a flying six.
Franky had his shogun, Brook is still fighting, Sanji is still fighting.
Robin case show: Strawhat improve themselve during the 2months, one gain new powerup, someone just get overall stronger.
Like Zoro said in past, they get stronger with each island they across, Robin proof it now.
No that´s not the point.
You were referencing Geo, Plex and so forth in a point they never made, or give me a quote that they did.
Geo, Plex, Veku and I (others i do not remember) argued that such a thing like zenkai boost does not exist. Characters are not getting stronger or are stronger because they traveled islands unless they actually show they got stronger, whether that´s Oda showing new techniques, or they are able to do something they were not before.
Robin literally training for it and showing a new technique proves our point, not yours, Robin got stronger by actually showing she got stronger, it´s something she never showed before. Just like Nami showed by having Zeus and far more AP, or Usopp showed by awakening CoO, or Chopper literally explained over three pages how he got stronger with the help of Caesar, or Sanji getting a new suit and immediately telling us how durable it is, or Zoro getting a sword and literally telling us "when i master it, i will be that much stronger".
The group i mentioned, including me, never argued against this, we argued you can´t assume people get stronger if they do not show they got stronger, pretty easy concept.
So no, Robin showing a new technique is not a proof of zenkai boost.