Your sleep will not slow down boot up.
Originally Posted by jc-Treo
What it does is make sshd try to start, fail, sleep 20 seconds, try to start, etc. until finally it is able to start. Any time it fails, it will sleep 20 seconds and then restart. Each time it needs to start, depending on random timing, your retries might hit it just right, or you might finally start sshd 20 seconds after it could have started. Statistically it should on average start about 10 seconds after the earliest possible start time.
The idea behind upstart is that rather than polling like that, starting can be event triggered. In this case, the "started LunaReady" event seems to accurately predict when ssh can properly start and sshd will be available immediately after LunaReady, every time.
If you reboot your tablet and start trying to connect via ssh you will see what I mean.
Far more annoying for me than the wait to get ssh at boot are the times when sshd must restart during normal operation. Yes, it happens, quite frequently. Having a sleep 10 (or your sleep 20) was VERY annoying in the middle of whatever I was trying to do. Using LunaReady the sshd restarts immediately and I don't see any delay.
Either approach seems functional but I didn't like the waiting when I tried it with a sleep 10. Personally I'm much happier using LunaReady.