Start with what the prompt is for
The decision has almost nothing to do with how complicated your topic is. It comes down to one question: will you use this prompt once, or will you use it again and again?
A one-off question, a quick email, a random idea you want fleshed out: the standard rewrite handles these fine. It catches the obvious problems, a missing role, a vague goal, no clear format, and hands you something usable right away. There is no reason to slow down for a prompt you will type once and never touch again.
Where the standard rewrite starts to fall short
The standard rewrite is fast because it only looks once. It fixes what jumps out immediately and stops there. That is exactly right for most prompts, and exactly not enough for a few.
If you are building a prompt template your whole team will use, writing something for a client, or you have already tried a prompt twice and the answers keep missing the same thing, that is a sign the problem is not obvious. It is buried. A contradictory instruction, an assumption you never stated, a detail that only matters in edge cases. A single pass will not catch that. A second look at the draft will.
What deep rewrite is actually doing differently
Deep rewrite does not just try harder in some vague sense. It adds a real second step. First it writes a draft the way the standard rewrite would. Then it goes back over that draft the way a strict editor would, looking specifically for what a first pass tends to miss: instructions that quietly contradict each other, missing detail on what counts as a good answer, and assumptions that were never actually written down. Only after that review does it hand you the final version.
That is why it costs a little more time. You are paying for a second, more critical read, not just a longer prompt.
A simple way to decide
If you are still unsure, ask yourself one question before you pick a mode: if this prompt gives a slightly wrong answer, how much does that cost me?
If the cost is low, you just re-ask, use standard. If the cost is high, the prompt becomes a template, goes out under your name, or feeds into something else, use deep rewrite. The extra time up front is small compared to what a repeated, unnoticed flaw would cost you later.