why can't I send all characters on a task at once?

So, all my characters are free, yet I am given some weird options like 'send 65 on a 1 hour task',...'send 30 characters on a 24 hour task' etc

is this the way it's supposed to be?
that's garbage...if i send 30 people on a 24 hour task, then need to go to the trouble of sending the remaining 70 myself...whats the use?