There are a number of conditions that have to be met to set the O2 sensor heater circuit. It's more than just the 55mph with deacceleration runs. Prior to that you have to idle under high electrical load (rear defroster, headlights, AC, etc.) for 2.5 minutes. Google the GM ecm monitor drive cycle. The GM cycle has worked for all cars I've tried it on. Some have taken a couple of complete cycles, none have required 3 yet.
The drive 55 with deceleration is the toughest. I always fudge it on the high side (60-65) so I don't get run over. Hasn't been a problem. For deacel, pulling into the right wide shoulder/breakdown lane on a freeway with light traffic with the flashers on is the safest way (for me), but the debris can be rough on tires.
In Nevada and for Federal, the Evap can be in a not ready state and still pass. Evap in a fail state, the smog test will fail.