How do you use red dot sights?

[kiakarimi]

how do i adjust the red dot at different distances? Do i just shoot a few shots, and line the dot up to where the paint hit and then i'm good to go forever? Or do i need to do that every time, or what. (i know alot of you think sights suck, but i'm just experimenting) Thanks for your help.

[MINDofSIN]

Well, I use a Crossman sometimes and I marked off 50 and 75 ft with a black marker so I don't have to worry about the guess work in my trajectory.