Anaplan (as with computers in general) is optimized for numbers and Booleans. Text formats use more memory than any other format due to the way computers need to store the data. Minimize the use of text if possible.
Set to BLANK rather than leave empty or invalid text.
Related to Rule:
2.02-04 Text Strings
Questions on this topic? See 2.03-02 Try not to use TEXT as a format, or limit it as much as possible in our Planual forum.