How much time does it cost to lose uptime again?

The uptime is a sliding average over about one month. In the beginning, you can gain about 3% per day when constantly staying online. Later on, when you are at, say 80%, it is very hard to gain more online time as you need to be online for about 20 hours every day just to hold the average.

The same holds for losing uptime, but the other way around. If you have an uptime of 100%, you lose about 3% per day when staying offline. At 20% however, the loss is only at about 0.7% per day.