Urgot's Lock-On mechanic is inconsistent and not mentioned anywhere

So i was in practice tool because sometimes W was locking out of people and i found this:
Q locks for 5 seconds, in the first clip i Q'ed twice waited one second and got full lock on the furthest dummy, and the last attempt i waited two seconds before using W and the lock ended shortly before the W
E seems to lock only for about 2 seconds, as you can see i E'd a dummy walked around in W and without exiting range halfway trough W the lock ended
Now, W tooltip mentions locking on to targets nearly damaged by his other abilities and his other abilities don't mention separate lock ons, also R seemed to lock for about 4.5 secs but since i couldn't be certain im not posting a video about it.