Using Quietrock drywall AND Rockwool Sound Insulation?
As you have noted too, sound proofing is a complex topic. Some published success stories are based on questionable data, others are based on specific cases, typically a basement / home theatre, or maybe a music room.
Sound proofing is expensive in terms of labour and materials, making it difficult to attempt by trial and error.
If your case falls clearly within the conditions for established practices, then those practices are your best bet.
I have found that rockwool provides mostly attenuation along its length and less laterally. It's great for stopping noise travel in joist spaces and other boxes, but less effective through it's mere 3 inches of thickness. Despite these reservations, stopping noise travel has an overall benefit, even in a wall, as noise entered at a weak spot in the wall (crack, outlet box, coupled vibration) does not travel to exit at another weak spot in the wall into an adjacent room. However, this is not your use case.
Your use case involves mostly higher frequencies, not drum-thumps or foot drops, and they emanate from any wall or window into the open.
Luckily higher frequencies are much easier absorbed or reflected.
If your intent is to sound proof an isolated out-building (garage) for the benefit of the neighbourhood whilst enjoying woodworking, there are a few easy steps you can take:

Make sure your inside walls are solid (crack &amp; gap free) and heavy on the inside (e.g. double 5/8 drywall, mudded and sealed). This contains the sound by reflection.

Apply absorbing materials to the inside of the noisy space: it absorbs the sound as it reflects off surfaces, and will reduce the amount of high frequency noise emanating from the garage, no matter where the absorption is placed. You can even apply noise absorbing pads to the ceiling where it is least likely to collect saw dust. Best to use fire-retardant materials or pads.


The additional benefit of the inside-absorption approach is that any small exhausts or other small venting passages are no longer critical elements in the sound proofing.
It also makes for a more pleasant working space.