I like to be able to feel some pressure before it trips. My current rifles all have old style Remy triggers that are adjusted pretty light; however, I will say that by the time I get to the end of a 20 shot string it's starting to feel too heavy. I'm thinking that I'm going to go Jewel when I build my dedicated TR rifle.
Bench rest you can go as light as 2oz safely, but if you use an adjustable trigger like a jewel I would work my way up, or down, to that weight. I set my triggers for tactical to about 16 oz. But If I shot on the bench one shot at a time no speed work I would run lighter.
I like a good, two stage, breaking around one pound, years of shooting double action revolvers with 10-12lbs trigger makes the 1 lbs really light to me.
About 1.5-2 lbs is about what I like, but admittedly that is higher than what most of the average F class shooters are running. The real light triggers are just too light for me.