[Matrixbeast]

As a quick counter argument the marathoning case, when you have to wait a week per episode, it's a lot easier to just lose interest. You have to move at the show's pace, not your own, so when things start slowly, it can lead to about 2 months worth of episode before things pick up, so even though it's only about 22 minutes a week, once a show starts losing you, it's harder for it to keep you invested.

As for everything else, it just comes down to individual taste. Most people use a 5 episode test since that gives the show time to set up it's characters, establish it's setting, it's plot, and tone (Though tones shift, the first couple episodes do (Generally) let you know what kind of show it's going to be). So it gives what some people see as a good taste of what's to come. So if it can't grab one's attention in 5 weeks, why should someone give it 45 more weeks to start coming together?
I understand it's not a perfect system (Using your example of Blade, yeah, the first 15 episodes are a bit of a slog, and many people would've dropped it using the 5 episode test if not for most of the forum vouching for it). It just has to do with patience. When the character who acts eccentrically and yells randomly starts prancing around during the early episodes in a clear act to catch children's attention, it can wear on someone's patience, and just decide that a series isn't worth continuing (And this isn't specifically targeted towards Onari. Mario from Zyuohger was shaping up to be the same, but they toned him down by episode 3-4, while other Sentai and Riders have featured much of the same (Wizard didn't, but it had it's own problems concerning the cast)).

I see where the frustration comes from, but returning to a show you just don't care about week after week on the hopes that it might become good gets difficult after so long.

I don't feel people are having unfair standards against Drive and Ghost because Gaim was good. Double was great, but people aren't rallying against OOO and Fourze as bad series. It's not a case of people having unfair terms and standards for deciding whether or not a series deserves their time, but rather how a series decides to handle it's beginning.
Gaim's beginning wasn't indicative of it's final quarter at all, but it chose to be lively and energetic while managing with a subdued cast to prevent people from rolling their eyes when character x or y appeared. Drive opened with a police force that felt like the KRC without any of the establishing moments that made you care about them, all bumbling around with props and one policeman throwing a tantrum when Shinnosuke showed up.

Gaim can be overhyped, agreed, but people aren't holding Drive and Ghost to Gaim's standard. People are just finding the flaws in the opening episode to be too overbearing to keep coming back to week after week.