Numerous times, it has been explained here that the weather is unpredictable, which is understandable. A post that I just read said it was once 55 degrees F in the Shetland Islands!
You want to be prepared in case a storm kicks up, and you want to be ready in case it's hot (55 is very hot to me for winter weather).
So, you wear your outer waterproof pants and probably a base layer of wool and then a mid-layer of perhaps fleece. When it becomes warm on an excursion, do you then remove the waterproof pants and then mid-layer while you're on land? (Then, obviously, put the waterproof pants back on). That seems like a lot of hassle.
I'm just trying to figure out logistics of layering and shedding.