[Suzu]

I feel that with Kamen Rider, the 20 episode mark is more of a point to fully grasp the show as usually, there is some change in tone or pacing of the show around that time. Back when I started KR, I never expected OOO to go in the direction it did at about half of the series (the whole purple medal plot etc.). Especially when individual character plots are mostly only fully revealed in the second half of the show.

Also, some shows start off feeling meh, but really take a turn for the better when you can put the puzzle pieces together at the end. The first halves of Blade and Drive were not very amazing when I watched them the first time, but boy, they did get a lot more interesting when you know what those things lead up to.

Also, I remember a lot of people complaining about Gaim during the first 20 or so episodes for being so (relatively) light-hearted and people were annoyed by the dancing and then BOOM. In the second half of the show everything just went to hell(heim). Judging from that, if you dropped Gaim at episode 5, thinking the tone of the first half was the general tone of the series, you miss out on quite a lot just for misjudging what you saw in the first few episodes. (on a side note, the darker events do start in episode 12, but the plot doesn't thicken as much as during the 20's).