could be a number of things. the way you rig the circles, leader size and length, hook pattern, size of bait relative to hook, how the bait is bridled etc
4-5 secs is a little on the short side and 1-2kg is a bit heavy for a free swimming meal.
to answer your question though, i've only seen and used enough tension to prevent an overrun on the take and thats usually freespool with the clicker on or very light drag.
as dan mentioned, once you've been bit, i would wait for time X ( 5sec < X < 5min) then slowly lift the lever to strike and pass the rod to someone that fancies a little winding practice.