Are powered a/c bumping into each other every five minutes?
Let's see (from memory and a quick bit of googling)...
C402 versus Rand, Coventry, Aug 08, five dead;
Grob versus Grob, near Cardiff, Feb 09, four dead;
Grob versus glider, not far from Benson, June 09, two dead;
Mooney versus Rans, IOW, Sept 10, two dead;
DA40 versus Rans, Shoreham, July 11, one dead;
Pitts versus Taylorcraft, Leicester, Dec 11, one dead.
Six collisions in the last three and a half years, a total of 15 fatalities...
No discussion yet of 'defensive flying'... I never, ever, operate OCAS under cloud streets, or fly over obvious big sources of thermal lift, or at ridge-soaring heights along ridges in conditions favourable to the production of ridge lift... But I only know not to do those things because I have been a cross-country glider pilot...
There are things I do when flying powered aircraft, too, to guard against meeting other powered aircraft, such as flying in IMC on otherwise nice days...