I am using ubuntu 18.04.5. When I shut down my laptop it takes too much time in my sense. So I tried this method to quick shutdown, it worked fine and my laptop shut down almost immediately. Now my question is, Is there any bad impact of this method on my PC's hardware resource?
The default timeouts of systemd are completely insane; typically it's 30 seconds, and they tend to add up. Check your current settings with:
grep -i timeout /etc/systemd/*.conf
Then make a decision if there is anything that could possibly really take 30 seconds to shut down, or if you want to reduce e.g.
DefaultTimeoutStopSec to something more reasonable like 10 or even 5 seconds.
IMHO any process that isn't finished shutting down itself within 5 seconds is seriously broken by design.