I don't think it should limit or impose on customers how they can spend their time.
That being said, I've wished before for a perk multiplier that could be used for special events or to give bonus yields for a "Early/Mid/Late War Week" in the past. So, I'm definetley for the idea of encouraging and influencing (with an incentive) participation for those who may wish to choose to participate, and not pigeonhole or deprive anything from those players who want to do whatever else they want.