For all you guys complaining about the fast travel... these are ~60 min episodes, and there's only what.. 8 total episodes this season? They have so much going on at once (so many story lines and info to fit in) that if they didn't fast travel, episodes would be massively longer, and there would be many more episodes in turn.
For Gendry's run... Obviously it wasn't just a couple minute run, or even just 30 minutes. He likely ran for hours to get back to the wall as fast as possibly (as evident by his collapse, similar to the Marathon story).
I don't know the proposed distance between dragonstone and where the crew is on that little island, but it's probably reasonable to assume it took a few DAYS to have Danny show up. Why would we need the writers to somehow convey this with a huge dialogic or otherwise? Any reasonable person who is a fan and knows the landscape realizes it's a pretty far distance, and the ravens probably max out around 20mph and the dragons maybe 40mph? Either way, they didn't just get there in a few hours, and I think that's pretty obvious.
sometimes i get the feeling people want GoT to be "realtime" like 24 was