. They should've met up by the end of episode 1
why? the show has to assume that not every viewer has seen all of the previous shows and is instantly familiar with the characters, so taking the time to reintroduce them and their universes was absolutely necessary. by episode 2 the characters already teamed up in pairs and the team got together in episode 3. that's a reasonable length for a show like that that also juggled side characters and villains.
but the few episodes that were left were clearly not enough to flesh out the villains, didn't gave the supporting cast much to do and basically cut out, what made the other shows so great: the side plots. instead we were treated with a very simple plot structure and a main plot that didn't make a lot of sense once you start thinking about it. there's were side plots would have helped (taking the focus from the main story a couple of scenes each episodes so that it doesn't get too obvious too quick how nonsensical it is)
some of the best scenes in Defenders were when the supporting charactes of the solo shows mixed up and got to talk to each other, but since there was simply no time for that, those scenes unfortunatley were short and underwritten. and again, made it very obvious how by the numbers those scenes were from a screenwriting point of view ("okay, so we have one scene were Trish talks to Karen in that episode and we put a scene with Coleen and Misty there and then we have Foggy talk to... and so on") If they had spread it out a little or had given them more to do those fanservice scenes would've had a better, more natural flow.
The same goes for the villains and their motivations. The fingers were... just there. We learned about there existence, we saw them, but what do we know about them other than what was needed to tell a very spefic plot? They had almost no character, except what was given them in earlier shows for those two that we have met before. Therefore the whole threat of the Fingers fell extremely flat. When there's no way to care about them, why should you? (The fact that they also posed no physical threat and that their plan made not much sense didn't help either, but again, with a little more time and little less rush to the great finale, those are things that could've been worked around)
Almost every flaw in the series is a direct result of an episode count that was clearly too low for the story they were trying to tell at a quality we were used to before (except Luke Cage)
