Nogzio

I just found the Alethi writing and was worried I'd have to wait for a translation, thanks guys!

Shallan "needing" 10 heartbeats to summon her blade in WOK was more of a psychological thing. She knows that she can summon a blade, but can't remember that the blade is actually her spren. She thinks she just has an ordinary Shardblade and those need 10 heartbeats to summon. We see her multiple times in WOR summing her blade without waiting the 10 heartbeats.

Only plausible explanation I can think of is Kaladin flying up quickly.... It's also possible (But very unlikely) that Renarin operated the gate, but I doubt that because he hadn't yet revealed that he was a radiant and he probably doesn't yet have the ability turn Glys into a shardblade.

One other thing to pay attention to is that not every gap between plateaus is possible to be simply jumped by a shardbearer. For instance the gaps around the tower are too big to be jumped. If a shardbearer was running from the Parshendi and got trapped and was unable to jump to the next plateau he would be surrounded and killed for his shards.