Yeah. That's essentially why I thought it was a good concept for him to think he should be able to defeat lesser enemies without using full power. Now, I'm not saying using full power as such is bad; indeed, you should always use sufficient power to quickly finish the opponent, but considering they are deep in the enemy territory without supply lines it would make sense to conserve energy.

However, of course he should have thought about that a few months ago because nobody is going to master any skills in five minutes. Kenpachi must be so badass even without bankai (or even a fancy shikai) or showy spells not only because he has extra reiatsu to spare but because he actually can fight and has who knows how much actual combat experience.