Is Hex: Pentimento even worth using?

It’s not worth using it by itself.

With plaything or some other shaman build (but preferably plaything because that encourages cleansing more), yeah maybe.

Seconding what others here are saying- it has a pretty decent place in some specific builds, but you're not gonna see much use out of it on its own.

It's not actually that bad, I expected to get less value out of it than I actually did while I was playing Artist- since I was lucky enough to get Plaything and Thrill on her pretty early.

I generally go one by one. But it depends on the killer.

I only have the build on Legion so i don't care about the second effect. Another killer might consider the healing slowdown.

if i put them up one at a time i deny the chance of both being cleansed at the same time

Pentimento is pretty great, but yeah, it requires specific builds to really shine and so Pain Resonance has turned out to be the more viable pick of the chapter.

When it does shine it really is ridiculously good though. Alongside Ruin, Undying and Thrill you will often get into a situation where you have cleansed totems to rekindle earlier on in rounds (they want to get rid of Ruin as soon as possible, they don't want to bless for 48 (or more) seconds), and so not seldomly you will have Pentimento and Ruin up simultaneously, even with 4-5 gens left to go, which is pretty oppressive. I have been using this on hit-and-run Wraith with "Blind Warrior" - White (which is the Mangled add-on) a fair bit and to lots of success, and the cool thing about it is that you tangibly benefit from two tokens here as well, as Pentimento combines with Mangled to make heals 44% slower (so 57 seconds for a Self-Care heal and 28.5s for other heals). But obviously this perk combo is particularly potent on all killers that can apply lots of pressure to begin with, especially Nurse and Blight.

Another particularly nasty build is Plague with Plaything, Pentimento, Thanatophobia and Black Incense. Plague already benefits from Plaything more than most killers since survivors will be injured and noisy and therefore even more threatened by the Oblivious status effect, put Black Incense on top of that and they frequently become free downs. And then Thanatophobia (which is obviously a great fit on Plague) combines with Pentimento to decrease repair speeds by up to 44%, meaning a gen will take a whooping 143 seconds to complete. And as a little bonus, Thanat also decreases cleansing speeds. Of course, this build will usually take a little longer to get going as you need to get people infected and hook them to get your Plaything Hexes up and for them to get cleansed in order to then rekindle them, but once it does get going it reliably grinds rounds to a halt. The last perk slot can be occupied by stuff like Corrupt or Ruin to help with the aspect of getting going too.

One downside Pentimento has is that survivors will usually naturally know where the rekindled Hexes are located at. While I've found that I can still often keep rekindled Hexes up for a long time for various reasons (such as survivors losing track of where they cleansed totems or not having the time or opportunity to get back to them) and while there are also ways to play around this downside (such as by tunnelling the survivor that knows where the totem is or actively defending the totem), some killers can protect the rekindled Hexes particularly well and are therefore also interesting: with Trapper you can trap the totem after rekindling it, which at worst gives you a notification if someone is trying to cleanse it; with Demogorgon and Lifeguard Whistle you get that same notification, and you can then of course even traverse directly to your totem; Hag can also trap the rekindled Hex, and this is especially useful in 3-gen scenarios; as Twins you can leave either of the two at the Hex to protect it; Doctor and Artist can snipe people off of the totem from afar.

No hex perks are worth using.