Should the length of varchar type in MySQL be a multiple of the field's encoding?

Question

I once saw someone on stackoverflow saying that it is recommended that when the length of the varchar field cannot be estimated, it is best to set it to an integer multiple of the encoding. For example, if the utf8 encoding is three bytes, then setting it to 255 is more appropriate. Is there any scientific basis for this?

Answer 1

I only know that the maximum length of varchar is 255

Answer 2

Prevent space waste and fragmentation

Answer 3

I think this is more appropriate.