Originally Posted by DoomKitty

Sometimes you can, sometimes you can't.
On one bike I got perfect chain tension with the axle right up in its drop outs; on my current bike it's just not possible, even with a halflink. A too-tight chain can snap and bend stuff; a too-slack chain causes a world of problems.

I persevered 'cos I don't like spending money, but I should really use a tensioner.