Steelskin+CwDT setup

Hi guys,
i'm an SrS player and i found a steelskin+CwDT+Inc Duration setup on a build an it looks pretty good. Do you know if i can level gems up until 20 or is better to lock em at some level to increase efficiency?
Thanks!

lock at 2 or 3

at lvl 20 it procs after taking 3272 damage.
do you have that much life?

Steelskin is more effective at higher levels, but as LoTharios pointed out the HP threshold for a level 20 CWDT is high enough that some builds might not even have that many HP.

For keeping it a lower HP threshold Immortal Call is generally better as it simply gives you a flat amount of damage reduction which starts at 25% and that scales no matter the content.

And Increased Duration is iffy with Steelskin.

Steelskin gives you a flat amount of damage absorption. Say that is 1000.

You get hit for 200. Do you want to increased the duration on 800? Or let the ability come off cool down so it is back at 1000?

Ive learned that optimal leve for CWDT is 9. Rest gems should be adjusted to this lvl and because of % Immortal Call is still most efficient from all Guard skills. Steelskin is OK but at high level so... use it as active skill.

It depends on to many things.
Are you using endu charges? Than do NOT use immortal call.
Inc durations is senseless, yes. Better grab a second gem.
And if your build got hp like 6k+ with fast regen/leech, lvl it to max lvl.
If you are more squishy glasscanon, use immortal call lvl 4-5 max.

The main point of IC with e-charges is not actually the increased duration.

As to which guard skill and the optimal level, you can run numbers all day but how it feels to a player in a particular build is a personal thing.