As you can read in the link at the end of the post, #HivePUD is an initiative by Hivers who gather every 1st of the month to power up some HIVE... Those power-ups aren't "more valuable" than any other done on other days...

Participating and showing support toward the chain motivates others to do it too... Of course, having bigger HivePower gives better upvotes that support other users, friends, and the community diversification...