Torque for receptacles and light switches
Generally, 14 inch-pounds is safe, although you can go somewhat higher if you wish
UL 498 (i.e the standard for receptacles in the US) calls out a tightening torque of 12-14 inch-pounds for wire binding screws (depending on size) in Table 123.3 as part of the Terminal Strength Test, and repeats that 14 inch-pound figure for 12AWG wire in 113.13 for the Terminal Temperature Test.  Given that you're generally dealing with duplex receptacles, and those almost always support through-wiring, 14 inch-pounds is a reasonable figure as 113.4 requires their terminals to be temperature tested with 12AWG wire if they aren't based on a 20A design, and most are based on a 20A design anyway.
Likewise, UL 20's terminal retention tests (found in clause 5.30) repeat those figures in Table 16, and Leviton's own specifications for their residential receptacles call out 14-18 inch-pounds of torque.