An infinite timer would be more suiting. For example: "//timer 0 1" would send one command every one second(s) and so on. The "0" in the timer means that it will never end; it simply repeats the command every allotted amount of seconds, which in the example would be "1" second. That being said, be careful using such snippets, it could potentially attract unwanted attention.
Alias spam { .timer 0 $1 msg $2 $3- }
Trigger: /spam SECONDS TARGET MESSAGE
To turn off: /timersoff (I think, I can never remember the timer kill switch.)