Two or three days is just right IMO, and some years ago that's exactly what we in my home pared it down to.

We took to the practice of going out on Christmas Eve to gather holly and ivy, which would be rather inelegantly strewn about the walls and beams that night while we got gently mullered on mulled wine. When the greenery is becoming a bit lifeless and a fire hazard (along with all the dripped wax and candle stubs) it goes in the compost.
Christmas over.

Now that it has become my norm, I must say that there's something exceedingly satisfying about a very simple, minimal Christmas. I much prefer it to the mass marketed, stress inducing excess I see about me.

Simply 'downsize Christmas' I would say to all the 'bah humbug-ers', and you will definitely enjoy your experience of what can be a gentle, intimate seasonal festival, much more.