1. One thing that I can see is that you are not using the latest WPML versions.
Please create a full website backup and then go to your site's backend > Plugins > Add new > Commercial > click "check for updates" and update everything to the latest versions.
2. Also, the time it takes for a translation job (or multiple) to complete depends on multiple factors like the number of languages that you are translating to (and you have many from what I can see), the amount of content, the server resources usage at that moment, the server limits etc.
So that is why you are experiencing different completion times.
I hope that you will find this information helpful.