danr wrote:So I'm learning that some skills are good to turn off after a certain point because there are diminishing returns.
My question now is - which skills, assuming you are using them, are good to train all the way to 27, and leave on permanently. I think the following:
I think the question is not meaningful without the context of a real-game situation. Most or all skills give *some* benefit all the way up to 27, even if this benefit is increasingly marginal. Some benefit is better than no benefit at all, so it isn't like you'd leave xp in your pool rather than improve your existing skills past the point of diminishing returns.
The question, then, is whether it's worthwhile to continue improving a skill in comparison to some other skill, which will change depending on where you are in the game and what the benefits of that other skill would be.
For instance, suppose you're a conjurations-focused spellcaster. You're going to have conjurations pretty high, and it gets slowly better as it gets higher. You've got translocations at 4 because you found Blink earlier and you already raised it to Excellent. You're hoping for Controlled Blink eventually, but you haven't found it yet. In this situation, more translocations give zero benefit so you might as well stick with conjurations even all the way up to 27. Putting more into translocations is a gamble that the desired Controlled Blink spell will indeed show up. If it does, you're already done with some of the work. If it doesn't, that extra work is wasted and you don't have the marginal benefits of the extra conjuration skill.
Even Fighting has marginal benefits toward the end when you consider the hp boost as a percentage function of your previous hp. A Trog-worshipper thinking about raising fighting from 24 to 25 for Zot should seriously consider bootstrapping Traps or Evocations or Throwing/Bows/Crossbows instead if they haven't already done so, because those are seriously valuable utility effects.
A real-game situation is, of course, going to be more complicated because you rarely have a situation where Controlled Blink is the only utility effect you might want that you don't already have the ability to use near-perfectly. The caster above is going to spend most of the game greedily trying to gather spells from many schools, like Abjuration and Controlled Blink and Haste and Revivication, and until the caster decides that Fire or Ice Storm is the next effect they want to add to their arsenal Conjurations is probably going to have to wait in the back of the line.