Why would you want to roll the dice. Generally on the on board will be just some of the pre-order options.

There are a wide range of opinions on UA onboard dinning -- better than last couple years but not a leader among domestic's carriers and definitely behind international. The seat and the lounge (& seated dining) are UA's strengths, not on-board dinning.

Some chose to dine in the Polaris Lounge and maximize the airtime to sleep.