Hello everyone! + tiny question with case statement

Hi everyone,
I join this community in the spirit that hopefully I can help (at least where I can) and learn. I feel a bit like a noob not knowing the actual formalities when joining a forum such as this but basically I started learning ruby this semester and I have found it strangely addictive.

Oh, with the tiny question...

I have a script that is basically as such:
#used to readjust dates when months are days are added to it

def function(x,y,z)
valid = false
until var == true
case z
when 1
#do something
when 2
#do something
else
var = true
end
end

The point I am really trying to get across is:
when the 'when' is satisfied, does it go to the next 'when' then 'else'

If it is appropriate I can post the code... it isn't excessive in length.
Any thoughts or input would be appreciated.

[edit] Apologies all, just my logic playing tricks on me

This should clear things up: