Generally the argument is never around saved computation but instead around composability. Lazy languages ensure that everything behaves like a value and in that domain operations compose much more effortlessly. You can't reason about operation as easily, so you don't, and the language can cope with making that work more or less correctly.

Which is definitely suboptimal in some cases!

I think honestly the goal should be reasoning about evaluation order statically instead of trying to find some clever argument such that laziness or strictness is clearly "correct".