The damage on those is normalized. If it says it adds say 60 then it uses the 3 second casting time for normalization down. So a 3 second casting spell will get the full 60 while a 1s cast spell will only get 20. When it comes to dots it looks at the number of updates and uses that to normalize the dot which caps at 5. So a dot user is most likely only getting +12 per tick and not the 60 you are thinking. The same applies for direct heals and heal over time spells.
Chris Kozak Programmer, Everquest II Go Buckeyes!