Jolt......mmmmmmm.......I remember when we could find it in NJ easily. Never had much affect on me, but I liked it better than 2nd choice Pepsi followed by others.....

Back to original question, if you are fairly hydrated, a beer, "maybe" 2 may be fine at the end of a flight, same for wine.
Dehydrated,or more volumne, likely to degrade next contest day. If nothing else, likely to mess with sleep.