I would say that a sensei can teach very effective but that woun't matter if one doesn't train effectively.
I try to do this: In every basic technique I do I try to train it as effective as possible to get a feel for how the principle behind the technique can be used against any other attack. This means e.g that doing tai no henko becomes much more than repeating the same movement over and over again. Every time I do that simple technique it amazes me how effective it is to neutralizes any kind of attack e.g a punch or a grab or a kick. This means that one trains agains many attacks in one basic and simple technique, instead of locking oneself to one technique - one attack and vice versa.
So my advice is
- Learn from your sensei and
- Train effectively!