that...requires you to have a 6 or 7 in an ability score. which isn't IMPOSSIBLE, just...fairly unlikely.
I've been playing with rolled characters a bunch. Chaos
more likely your lowest save will be a 9 or 10. more on that later.
I mean, with point buy or array, I usually have an 8. So -1 on top of the bonus. (I guess cloaks/etc are great)
it will for your strength, and maybe your con or dex if you take resilient dex and max it out. otherwise uh...no, it'll be about as close as the +10 was at level 9. which is my problem.
Yes, you get legendary resist on the stuff you invest in. That to me is completely ok.
Hell, I'd be ok with a mid-level character having one save they almost never fail
always, let alone X times per day. It isn't as if that breaks the game; most mid level monsters (let alone adventuring days, let along campaigns) feel like they feature multiple different types of save effects.
If someone can stonewall the push back from a giant because they invested crazy in strength? Great, that makes a evocative character concept realization in game.
With +9, you get an auto-save against your strong saves, and a decently good chance against a poor save.
By +20 you get an auto-save against basically everything.
A "decent reroll with a bonus" converts continuously into "legendary resists" by level 20, and it does so at a different speed on different stats. On top of this, it is a scaling bonus on pure-fighter defences; the Paladin 6/fighter 9 (or whatever) doesn't have "better" ability to use indomitable than the pure fighter does. (I prefer it when a single-classed characters class features aren't significantly better done by a multi-class character; I'm looking at you, Divine Smite)
....no? all the Indomitable uses are the same.
Being able to do something 2x a day is not twice as good as being able to do something 1x a day.
This is like "the second feat is not as good as the first". The 2nd can be almost as good; but by the time you hit 3, there is diminishing marginal returns.
(To express it formally: in a given adventuring day, there will be a bunch of opportunities to use indomitable. The more uses you have, the less important each use will be on average.)
You can see this on DMs use of legendary resists. If you had one, you'd save it for "omg I'm gonna lose if I fail", but with 3 the first one is often on "that is a lot of damage" or whatever.
A "classic" problem with every edition of fighter has been it gets a feature at low levels, and at higher levels it ... gets another instance of that feature. Be it a feat, another fighting style, or here another use of an ability (like indomidable).
Your first feat, fighting style, or use of an ability is
better than your 3rd almost always (there are exceptions, when the ability has self-synergy, but that isn't common). When you get a feature at level 1-5 as your class feature for a level, then another use of the feature at level 16-20 ... also as the class feature at that level, it means that the level 16-20 level
is worse than the level 1-5 level was.
This error is why 5e.14 had many martial classes multiclass levels 1-3 (or 4) from multiple classes; the level 1-4 features where as good, or better, than the higher level features of other classes, let alone the increased choice (because you can pick from more classes and subclasses) allowing more optimization.