I haven't checked for a while but most liberal computers don't have a setting for more conservative. Conservative generally have such settings.
On Oceanics you can vary when you want it to start beeping at you(consider that your NDL). Your saturation is represented by a bar graph with colors of green, yellow and red(mandatory deco required). There are probably about 8 or so dots that count up, sort of like tally marks, as you approach the NDL. You can set the alarm to start beeping at you on the first mark, or whichever mark you would like. I can't speak for other computers and their functions, but with Oceanics you can be so conservative as to allow you nearly zero bottom time, or much more than a Suunto would allow(and I don't see tons of divers using Oceanics getting bent).
For ultimate flexibility, I'd suggest using one's brain. Like with the Oceanic computers.......set them to the most liberal setting(it won't get pissed unless you hit that mando-deco red zone), and use judgment. "Oh look, it's colder than I expected, I'm tired from swimming in current and I didn't sleep as good as I hoped last night. I have 17 minutes of BT left. I should probably surface with 10 minutes left just to be easy on myself today."
What a clever idea, Joe Diver!