Our 4200 sq. ft. house when new was painted with paint from General.
On most of the door frames , baseboards and casing, the paint yellowed in just a few years. I went back to them and they said it was probably poor undercoating or priming of the wood, and contractors sometimes use lowest quality available. I believed them and bought their best white paint for my basement. All baseboards and mouldings were preprimed which you buy from the hardware store, and again the exact same problem occurred. It is a lot of work to repaint, but over the past few years and now using Cloverdale ( which many contractors seem to use ) the colour has stayed white. I even painted 1 moulding beside another with the 2 different brands and can see over time the result. Who wants to repaint again and again these areas that are very tedious. Hope this saves you time and money.