Most of the signature campaign doesn't allow leaving in mid of campaign! If you leave your whole works/stakes will be abandoned! That's why people hate extension in bounty campaigns! Though some bounty manager realizes this situation, that's why nowadays they let participants leave the signature after 4 weeks or after the first phase of bounty campaign!
There are some who still do not permit. This is why some users prefer to participate in bounty campaigns that pay weekly, although it is rare to find. Had it ben it is social media bounty, you right not find continuing, because it gives room to participate in as many bounty campaigns as possible. In fact, you can decide to quit when it comes to that and your stakes will remain, except in rare cases.
It's rare to see a campaign that still keeps the stake of participants that already leave the campaign.