During different events you will find that your troops are landing in the hospital or dying. These events could be another commander attacking you, roaming doomies, alliance exercises, etc. One may think that you should heal all of them all at once. But that actually isn’t efficient and you can end up wasting a lot of your speedups to recover from that if your entire drill ground has been decimated.
Unless you are logging off for a longer period of time (i.e. for the night), you should heal in batches. I’ve found if there are a bunch of alliance members online, healing in batches of “1 hour” usually will complete in seconds due to help. This strategy has the benefits of faster healing times as well as giving Alliance Contribution points for each time they help the alliance. These points have the benefit of being used in the alliance store to get things like shields, transporters, resources, shards, etc. for free.