As opposed to using CreateTimer() to run code in the future, there are various scenarios where you could just use a single float to do things such as, preventing code from executing until a certain amount of time has passed.
For example, all of the "m_flNext..." variables Source uses work this way. TF2 has m_flNextPrimaryAttack. This is set to a time in seconds, which is compared to the GameTime, which can be retrieved in SM via GetGameTime().
This seems like a lot of work for what is essentially OnGameFrame on the game server side.
__________________
Not currently working on SourceMod plugin development.