The reason you're training should dictate how you train. Squats and deads on the same day aren't an automatic no-no, they can be effective and they can also be a disaster. It depends on the trainee, and on volume and intensity (intensity as % of 1RM, NOT some sort of perceived effort). Limit squats and deadlifts in the same week for more than 1 week are tough, much less the same session. If you're only working with 80-85% of 1RM, then both in the same session shouldn't be an issue. Also fo importance is how long you're doing it....more than 3-4 weeks would probably burry anybody who is past beginning stages.