Alot of people think that denoising is a one-time thing, "do it once and forget about it". It really is not. A couple of years ago, I developed my workflow on how to denoise during my days of shooting macro insect (or rather, attempting to shoot insect). Sharpness and keeping noise level low is extremely important in that particular genre.
The edit by me, was denoised no less than 5 times and sharpened no less than 5 times as well. That's already 10 layers dedicated to denoising and sharpening. There's also other ways to deal with noise level, such as giving it a blur. In the end, you have to know very clearly on which part of the photo needs a denoising, which part doesn't, and which part needs just a little. That's because you can't escape the reality, that every denoise losses more details. Unfortunately, people have a mindset that denoising is bad, and it should be applied as little as possible - it couldn't be further from the truth.
Denoising aggressively might not be a bad thing because stuff like background can afford to lose all the details; that will just result in making your subject stand out more. Hence an aggressive denoise applied to the background actually helps the photo. Details in the wrong area misled the eye, giving a chance for the viewer to read a different story than the one you wrote.
Ultimately, denoising is just alot of patience and practise.