Personally, I think quantifying volunteering is not in the interests of democracy, let alone putting a limit on how much personal time someone wants to put into an election. If you really have to break it down, there are theories of economics that say the only currency that matters is time, because that's the one thing we all have an equal amount of. If a political party has more volunteers, then ostensibly it's because they are able to motivate more people to their cause. That is the true test of someone who has the support of the people who are electing them.
On June 7th, 2018. See this statement in context.