Smallville effect:
Everyone starts to discover the identity of the lead character, or certain situations happening on screen makes almost impossible not to think all characters are on the verge to discover/suspect the lead character's secret identity.
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Too many "super" characters crowding the show and making it more and more hard to consider "plausible".
So much to say, I'll start here. These points you make are not the Smallville effect or at least not bad things.
Discovering the identity - This wasn't actually a problem. We wanted this when it got to insane points like not telling Lana. which would make his life so much better. Maybe what you are really thinking of is "Clark Kent has a secret, what can it be". They built arcs on this and it got very annoying and detrimental.
By the Blur points they stopped doing this arc and the show was better for it.
Too many Super characters?
That was never a problem. We all loved this. Smallville get's props for this. The real issue was characters would show up and do nothing. Characters show up just to get captured and prove Clark is a better hero. They never developed. Green Arrow suffered from never being GA or needing Clark to save him. But we loved the Legion and JSA episodes.
The Smallville effect is dragging things out and never making good on a promise. Well Green Arrow has his costume. Arsenal, Huntress, Canary, Flash........all suited up. They aren't doing a before the mask.
I'd say Gotham may have the Smallville issues.
FOTW on Smallville also suffered from being teen problems manifesting as meta's. But by the time of the Blur, all that nonsense was gone. FOTW were actual baddies.
Now romance reeks of Smallville and CW in general on Arrow. It's so destructive and counter intuitive. Though I think Arrow has been working it out.
Now since we are on the subject.
Smallville big issue was that it was a Superman show trying not to be a Superman show.
I think Welling probably got over the Superman thing but the showrunners didn't want to. They got him in costumes. They did this.
No flights was a super duper stupid rule. They either broke or failed with Tights since they never made it.
Clark became Superman when he became the Blur. It only took him a few years to get the proper costume and name. Superman didn't need training or a trial period. But the show wasn't aware of this fact. It wasn't area that they had already completed their goal.
It was a mockery of the premise and it was frustrating.
Lois and Clark was about Superman. It just also focused on the romance between the characters and Clark himself.You never watch the show and go "Wait why is he wearing a Superman costume?". It was a show about Superman/Clark Kent but it wasn't a show only about the Superman identity like the 50's show was and really the movies.
Back to Arrow
It's not having these problems. It's having fun being about superheroes.