Adjective agreement with estar+de lo más

When using de lo más with estar, specifically, is it preferred or more common to have the adjective agree with the subject, as distinct from when using ser for example? I noticed the specific example sentences using estar both have adjective agreement with the subjects. So I wasn't sure if this was supposed to be indicative or if it's just a quirk of having examples that were chosen at random, and I can't seem to find an answer anywhere else...