Varys goes on a boat to Dorne, comes back with the Dorneish fleet, and comes back with Dany's mega fleet, we only see him in dorne with dany and the mega fleet, thoses scenes were months apart in universe, there is no reason to devote screen time to him traveling.
it doesn't matter if its in the same episode, you just have to pay attention to whats going on. Arya is a terrible example, half her scenes so far have been devoted to travel time... Lannister camp, crossroads, seeing Nym