In many random occurrences of Stargate SG-1, the stargate can seemingly open instantly while other times it appears to slowly light up random symbols before a wormhole opens. I am referring specifically to incoming wormholes as viewed by the receiver. I am also talking about using the plain old DHD.
For example, in "Redemption, Part I" at the start of the episode, Walter is taken by surprise by the sudden opening of the stargate as SG-1 is ahead of schedule. However, Carter is clearly shown using the DHD on the other side.
There are many other occurrences of the gate suddenly opening, but also many occurrences of the gate slowly "dialing" from the receiving end. Is there any specific set of rules to determine how the gate appears to open from the receiving side?