Which cruise? On the Sea, our only tenders were Belize and Cancun. We had an NCL excursion planned in Belize, so we were some of the first off. In Cancun, we were off the ship within about 1 hour of anchoring. Depending on what you have planned in Cancun, we thought it was a long, slow boat ride without much to see or do at the end. If you have something planned, it may be worth it.
Next time, unless I have a certain excursion planned, we will just stay on the ship and relax by the pool.