Guys,
Our SG fragmentation grenade has a 5sec fuse. It starts burning
when the safety lever spring-off from the grenade cap-top. You
should start counting-down when the grenade is thrown from your
palm, not when the pin is being removed. 
5sec is just adequate if you are a good thrower with good reach of
distance. The German's potatoe-masher was designed with a stick to
improve the reach of the grenade in the open.
Now that we have grenade launchers allocated at such proliferate
rate in our fighting orbat, maybe, we should have differential fuse
screwed on our hand-grenade so that we can choose the length of
stand-off timing. ie., a shorter 2sec fuse for room-clearing as
opposed to 5sec fuse for fighting in open. 
As a gentle reminder, as long as the safety lever is held in place,
the grenade will not explode. Hence, it can be improvised as a
booby-trap by tying the grenade with safety pin removed but
retained in it's shipping container. Attached the free-end of the
string across a road or a door that you expect enemy traffic;
volia, you have an improvised anti-personnel IED. A common trick
used by Thai soldiers and, no doubt, others in the region.
