At Costa Linda the rule is 2 hours. I'll go down and take a palapa around the pool if available and then spend an hour in the pool jogging so the 30 minutes would really be a problem. 2 hours works for me and, even in high season, there are always palapas on the beach available. The pool palapas are at a premium then. Haven't run into any rude people except, occasionally, tourists. The man blowing his cigar smoke in my face at the casino (I just moved), etc.