Timer events: pros & cons?

[teddyq]

I've often heard things like "you shouldn't use timer events". Why is this exactly? What are the reasons not to use timer/always events, and how would you replace them? In which kind of situations they are the best alternative?

[SEELE]

well, mmf does things (refreshes) as fast as it can; however sometimes it can't archive the expected speed... when this happens everything which uses timer events eg. 'every one second' will become out of sync with everything else.

There are soo many ways to replace them, one of which is the egg times extension.