Not sure how it is for everyone. But i just jumped on, picked a flotilla that wasn't too close to be being completed, and started a ground mission. this ended after about 5 waves as the 100/100 murex was completed, now there are no instances with slots i can join. I get plonked into a new empty flotilla with 0/100 done and only an hour remaining and there is an hour wait for the next reset. so i guess it's about luck when i log on, unless i sit and wait for an hours or so each time?