Our tree goes up the weekend directly following Thanksgiving (sometimes the weekend after that) and stays up until 4-10 days after New Years- so about 35 days total. Some are fresh cut, some from a tree lot, so time from actual felling varies. In 20 years, I have only lost needles once before XMAS. The rest stayed full and relatively moist for the entire period. They will start to drop needles at the end, so removal is expected to be a little messy. Thank goodness for the Shop Vac!

I'm particular to Douglas Fir, but have had several varieties over the years.
We too make a fresh perpendicular cut at the bottom, right before we put it in the stand. Not too particular about how often we water or how much. We do a 50/50 mixture of water and 7-Up (or Sprite) which we feel helps with the needles.
Talking to some colleagues this year about tree tips and tricks - a few do the same and I heard one say they add Tylenol into the water as their secret recipe.

We normally lay the tree on a sheet and wrap it up during removal to help with the messy needles. My best removal was when we had a flat right on the Thames. One dark night as the tide was going out, and woosh - right off the balcony. Never saw that tree again! That was also the year we got the tree and brought it home on the Tube during rush hour! "Excuse me." "Sorry." "So Sorry." "Pardon Me"...

Fun Fact: pine sap is hard to get off your hands, even with soap and water. After you wash, run your sappy hands through your hair. The natural oils will neutralize the remaining stickyness. I'm not taking the piss here. It really works.