How often should I re-ask a Spark question?

If you'd like an ongoing understanding of something that you want to measure over time continuously - such as "are you willing to take your children out of school to go on vacation?" - then we recommend fielding the question every year. 

If you need an understanding of how consumers are going to react to a one-time event - such as the 2019 Tax Reform, then you only need to ask the question once.