Lets asume that we got a command block on repeat mode set on always active.
And you Have the command: /time set 50 in the command block.
Naturally you'd think that it'll add 50 tick to the time value every tick.
Well it doesn't really do that... It actually adds 200-300 ticks every 1-2 seconds.

This is wrong... In order to be able to build good maps we need an foreseeable behaviour, that would work the way you'd expect it to work.