One question but where did the White walkers get the giant chains from?
As ShanklyGates says - plus they may well have been bringing them along anyway to use on The Wall / in the fight to get past The Wall
I didn't have any problems with the skewed/accelerated timelines in the previous episodes like many others (the only things I objected to was the quickly thrown together KL expedition in the last episode and the fact that the whole "bring the zombie back to Cersei" plan is a bit stupid), but in this one it did completely distract me from the action. The magnificent seven were stuck surrounded on a rock in frigid weather, with no food, water or fire, with the whole army of the dead just staring at them for no particular reason. From that position, there was enough time for Gendry to run back to Eastwatch, send a raven (as in an actual bird) all the way down to Dragonstone and then wait for Dany to fly back all the way up beyond the wall to the rescue. Seriously? How long were they on that rock staring at the wights, three fucking days? Ludicrous.
Some great set pieces and visuals, mind, but for the first time this season I really got the feeling of a clunky, disjointed episode, story wise.
As Sam points out in episode 5 to the Maesters - they are respected and trusted, if they sent ravens to every Lord in the land to send me north to fight the Night King people would go. So it's not
just Cersei they'll be showing the capture wight to - once word gets out - and previous skeptical/unbelieving people see it, word will spread - and help in the fight...
Re the time on the ice rock... 2 days they spent there (with an injured Thoros dying in the night), with Jorah mentioning they are out of water, the ice will freeze and so will they - so the Night King doesn't have to do much at all but wait and not risk any (or many) of his men... though likely hadn't much clue that help was on it's way...
Gendry was the youngest, fittest and likely quickest - and reached Eastwatch as the night drew in. Ravens and dragons apparently cover the ground quite quickly - and also have the advantage of travelling 'as the crow flies', as it were. Dany may well have rode those dragons extra hard to get there as quick as she could too - not just for the mission - but also her feelings for Jon too
(as we saw in episode 4 with Drogon flying low over the river to burn some Lannisters - they move very swiftly...)
Littlefinger had a better teleporter to move around Westeros so quickly in the early seasons though