How bad is adding new column each time to compare the fixed values?
If the values in one row are not related to each other, adding columns is pointless.

Writing values into the new columns requires rewriting entire rows, and reading a value requires reading the entire row (up to the desired column). So that schema becomes increasingly inefficient.

Put the week information into a separate column:

week  name       value
---------------------------------
  1   Title      SomeTitle
  1   SomeProp   SomeVal
  2   OtherProp  PropValue
  2   Title      SomeUpdatedTitle


With this schema, you do not have to pick specifics weeks to compare; you can also search for weeks where something changed, or compute distances between changes.