Basically what you use them for is that that during an update you'll be able to conduct multiple operations. What hapens is that when a nation with WA membership on it updates during major or minor, any endorsements that it gives afterwards won't count until the next update. However, if you resign from the WA with that nation after it updates and enter the WA with a new one, you'll be able to continue going during the hour and contribute to the fight in later updating regions. You want to have enough puppets so that if it is a super busy update you don't end up running out, and you want to have applied (but not opened the confirmation email and clicked the link) so that you can switch quickly.