For the average player 4 to 5 seconds isn't that much time.
Really? 5secs is not enought to geat out of the small radius 1 shell? (since second anf third would come at 10-15sec)
Well, let me tell you something.
Mechanized company arty comes with 6 secs and it comes all over the circle, not just center spot.
CAS Stuka - 4-6secs depends where you use it.
Incendiary - same thing 4-6secs.
Mechanized doctrine (the one with assault grens) also has off map. 5 secs from the first red flare.
There are already abilities which work after 5secs and they do it on the bigger area than single shell.