Board Thread:Game Discussion/@comment-26719180-20160121103610/@comment-26715739-20160121110636

You can watch an ad to reduce the service/upgrade time. The general experience seems to be that this ad is served from the same pool as "watch ad for GC".

So it will depend on whether you see the gain of 1GC to your total as more/less valuable than shaving 30% from the service/upgrade time.

Most people would suggest you should watch the ad for GC and not to reduce upgrade/service time. Especially since the overall pool of ads seems to have become much reduced.