For this project the homeowner had a living room/kitchen shotgun combo with a back hallway to have painted. This involved the baseboards, door frames and doors, ceiling and walls.
While the color change was not that drastic there were three areas in this small area that gave an issue and can serve as a great example of what looks like it might be a problem sometimes is not.. and sometimes what you least expect would be a problem becomes one.
In this situation we had a red wall that would no longer be an accent and instead return to the main wall color. Reds can always be problematic but in this case two coats of wall paint covered it no problem. The yellow wall was repainted yellow. Sounds simple right? This along with the back hallway that was green would be changed to yellow. Both walls required three coats of paint to properly fill in which taking the green to a solid and vibrant yellow was expected to give some issue.. generally yellow over yellow does not but the old color being more of a goldish yellow and the new one being a true bright yellow in order to get the full color effect a third coat was needed to fully block out the gold. Simple solution of course but the kind of things we warn about that can happen with certain colors clashing with others.