AndIf would be better as you are evaluating multiple conditions. I find personally If to be for singular evaluations (thats not to say it cant be used for multiple as it can)
https://forums.modx.com/thread/?thread=63762&i=1&page=1
(id copy the URL as its not taking the parameter)
You would need a way to tell MODx what day it was though
[[AndIf? &condition=`[[day]] EQ Monday|[[day]] EQ Tuesday` &operator=`OR` &then=`Display Woof` &else=`Display Baa` ]]
Obviously [[day]] is the snippet to work out the day EQ is the item to set against and 'Monday' is the subject.
I use AndIf far more than If tbh.
AndIf will take all of the paramters If does also
Good Luck