Yes, he was ...
This is not the trooth. For example did he rode best time on final climb to La Plagne in the Tour 1995 (stage 9), Nobody could follow him (Zuelle had 5 Min. advantage when starting the final climb).
http://cyclingnews.net/results/archives/letour/stage9news.html
The day after he was 2nd in alpe d huez behind pantani (who rode record time to alpe d huez with madeleine and croix the fer in his legs, faster than armstrong in time trial). zuelle and riis were the only ones who could follow indurains
back wheel and did not do any work ...
Do you remember legandary mountain stage to sestriere, when indurain was 2nd behind chiapucci?
Also he once attacked succesful on flat terrain
(Stage 7 Tour 1995 to Charlroi), which we have not seen by much tour champions. Bruyneel could win this stage, because he did not make any work in the wind ...:
http://cyclingnews.net/results/archives/letour/stage7news.html
Indurain was only once 1st in a mountain stage. But he was very often 2nd and very often rode best time on final climb. In opposite to Armstrong he very often left the mountain stages to others. And he did it also in an other way than Armstrong.