They aren't neccessary because last night i had a DILD, and i just realized hey im dreaming. With no Reality Check, and usually i never do reality checks unless

1. Something really strange happens and i start to question things
2. I'm already lucid and i just want to try it anyways.

It does help confirm it though just incase your not too sure.. That may happen to you because sometimes dreams can be very realistic. Mine tend to have realistic properties but not tottally realistic. Like my dream last night i had no pants on.