When you have target selected:
[18:49:54] You prepare your critical shot (4.5s to fire, target is in range)
[18:49:59] You are ready to fire!
[18:50:14] You are too tired to hold your shot any longer!
So after 20 secs you're too tired to hold your shot any longer.
If you line up a shot without target your character looses the "shot -stance" animation after ~20 seconds but you're still having your bow drawn ready to land shot:
18:52:13] You prepare your critical shot (4.5s to fire)
[18:49:54] You prepare your critical shot (4.5s to fire, target is in range)
[18:49:59] You are ready to fire!
[18:50:14] You are too tired to hold your shot any longer!
So after 20 secs you're too tired to hold your shot any longer.
If you line up a shot without target your character looses the "shot -stance" animation after ~20 seconds but you're still having your bow drawn ready to land shot:
18:52:13] You prepare your critical shot (4.5s to fire)