I've always looked at it like this.... they never give dates, like when Varys went from Mereen to Dorne, and then back to Mereen, they didn't say March 8th, Vary's leaves Mereen... March 20th, Varys reaches Dorne, March 24th Vary's leaves Dorne bound for Mereen, etc. We saw him bounce around in one episode, but how do we know the time that has passed? If they locked in dates or timeframes somehow, that would be different. Like if a female character was 9 months pregant, and someone left to go on a long long journey by boat, and that person got there, accomplished whatever goal and sailed back, and the chick was still pregnant with the same kid, then we have a problem. Barring that, I just always assume that the time that passes between scenes in an episode is whatever time the story arc needs, and as long as they don't fuck up, it doesn't bother me.
I used to watch One Life to Live... soap opera that went off the air a few years back, and they regularly fucked up with travel and time. For instance, the characters all lived in a Philadelphia suburb, and there was a storyline where one character went into hiding in like Toronto... and another character finds out and heads off from PA to Toronto to find her, and they literally went there and back during the same episode, while some other characters were siting in a diner

. So they locked in the day/time because of the characters sitting in the diner, and then fudged the travel time by making their friend make that round trip