I mean, "common classes" is relative, if you're fighting calvary classes, you're fighting calvary classes.

She can be great for survival as long as the enemy lacks buff removal. With her S1 at L10, she can go over 50,000 HP with just a few turns of waiting. With a Black Grail, she can also hit pretty hard with NPs while ignoring the demerit. She isn't fast but can be a fun beat stick.

If you are Buster looping with Koyanskaya and Oberon, she can do the job for mixed Cavalry classes but only with Kaleidoscope. Still, an acceptable option there.

I also used her in an early Grail Front. Parked her on a healing spot and let the enemy come to her. She does not do well against the Knight classes, but watching her smash a Saber turn after turn, ghen going down only to recover with her buffed 50k HP was amazing. She crushed it for me.

If you want the fastest clear every time, ignore her. She isn't made for it. Her job is to have insane HP and ignoring damage while she punches enemies.

Totally subjective here, but I get the feeling, she's one of, if not THE strongest of the Alter Egos in terms of direct damage.

I never regretted rolling her.

Can't seem to find the video of her looping with Summer Chloe system, but let's just say, with that amount of damage, doesn't matter if you deal 1/2 damage :P

It's just a matter of how bad you want to farm with a servant.

Who cares? If you like a character, roll for it. That's like, the point of the game.

Any servant is worth it if you like them

If you really like her she could be the worst servant in the game and would still be worth rolling for. As she is, she's good. Both as a DPS and farmer (especially with the best possible setup including summer Kuro).

She's good.

The problem with Summer Chloe setups is that they require too much party cost. Locks you out of taking a full SSR CE lineup. That might not be a problem when farming for a specific event currency, but it greatly diminishes the amount of bond earned during free quests, for example.

As for Kingprotea herself, I'll just reiterate what others said above: she's really strong for CQs, but is built for slower approaches. She technically can farm, but the damage will be lackluster unless you have Oberon and/or do Summer Chloe shenanigans.

To be fair, the party cost is only an issue for lotteries, which you wouldn't want to use her in anyway because there are too many button presses. As for daily free quest farming, I personally wouldn't use any setup requiring plug suit at all, let alone the absolute optimal one. But it's always good to know you can farm with a particular servant if they happen to be a favorite.