Not so much breakage (on the street) but wear. It's recommended to use a small grinder or sharp file to polish every spring & damper edge in contact if you use aluminum or titanium spring washers. The usual sharp edges even on used springs or dampers will saw thru softer alloys in short order, if you rev the engine to the point where light-alloy parts make a difference.
Ti or aluminum washers also can be had in various assembled heights, changing the way the rockers contact the valve stems. So you need to know what you need. And of course, the stock multi-groove intake & exhaust valves should be consigned to a trash bin before they break and destroy the engine or at least the head(s). Good luck.