Even though I've traded for what feels like eons, I've spent some free time the last couple of months putting together automated strategies in MultiCharts, and it's great fun. Whilst experimenting with various types of exits I've been thinking...
There are many reasons for trading with a stop loss; keeping losses small can be one of them, avoiding a catastrophical loss can be another. The latter I'd say would be related to the amount of leverage applied to your position (or insanity like being long C last fall, even unleveraged). Ultimately, it depends on the system of course - what kind of movements you're trying to capture.
But if you can stand the swings, I find time based exits without a stoploss to be the ultimate exit strategy - with a few assumptions, of course. So, let's say you're trading a portfolio of 10 uncorrelated systems with no (or very controlled) leverage, why wouldn't you move the catastrophic loss far, far away where it (hopefully) will never get triggered - and rely on a time based exit?
I hope someone can provide some interesting talking points on the subject, keep in mind I'm a system developing newbie - although I've owned the Ralph Vince books for 10 years.
Yes - stop assuming that an arbitrary choice must be ideal