Lucky 100 isn't very good for push processing. It has a rather thin emulsion/low silver coating. It rapidly increases contrast, with blocked highlights, as development gets longer. Especially so when an M/Q type developer like D76 or ID11 is used.
Many of the examples on the 'net- esp. flickr- don't really show 'pushed' luckypan. Only underexposed and overdeveloped examples shot in good light. Good pushing abilities will only show in examples shot in poor light with extreme contrasts. Plus, a lot of these examples look to have scanned directly from the negative, where a good 1 - 2 stops may sometimes be obtained even with a very thin negative.