部份原因是这种研究花费时间太长。

Part of the reason is that this kind of research takes a very long time.

youdao

缺点是这些政策的决定者是政客，经济消沉时他们要达成正确政策花费时间太长，同时也不愿意在繁荣的时候加税。

The drawback is that it leaves decisions to politicians, who risk taking too long to agree on the right policies in a slump and are unwilling to raise taxes in a boom.

youdao

And, sad to say, at least one of our tests produced an output that we were unhappy with.

很不幸的是，至少一个测试输出我们,是不满意的，它花费了太长时间。

麻省理工公开课 - 计算机科学及编程导论课程节选