Opus 5.5 on low is good if you are relatively sure a given task is straightforward and time spent gathering background information is purely wasted or possibly even detrimental. Opus 5.5 low seems great at doing the most obvious thing based on the prompt without thinking much about it.

I agree - Opus 5.5 on low is a really great model if it has some direction and the tasks aren't complex.

If the tasks are complex cranking Opus up to high or xhigh and getting it to delegate to Opus low subagents is pretty effective and much faster than running everything at high.