Q. Can I shorten some of the ceremonies and prayers found in the Siddur?
Ask yourself what your motivation is in wanting them. Probably you want more time for your own concerns… more time for money or gossip… more time to focus on anything except your character and soul…
When the sages discuss ways of abbreviating the Grace After Meals what they have in mind is getting back to work and not taking undue time away from an employer. That’s a means of being ethical and thoughtful, not just promoting your personal advantage.
Here’s another example of when a short version is appropriate: in 1941 during the London Blitz people rushed to the bomb shelters as darkness approached, and religious Jews were worried about what to do on Seder night.
Dayan Yechezkel Abramsky of the London Beth Din explained what the real essentials of the Seder were and showed how all could be covered in 15 or 20 minutes, allowing people to get to their shelters in time.
The motivation was entirely valid. Lives had to be protected and had to be combined with the observance of Pesach.
In time of danger to life or health it is not required to drag out a service or observance. But when there is no emergency a person should take their time and savour the spirituality of the moment.