It was too expensive, to say nothing of the time it wasted.

这太贵了，更不用说它浪费的时间了。

《牛津词典》

In fact the time spent on it had been thoroughly wasted; much more so to my mind than if it had been wasted in doing nothing.

事实上，我们花在这门功课上的时间完全浪费了；而对于我们的心灵，这比什么都不做还要浪费。

youdao

Then later that day, you may feel like working some more, so far you'll have done ~5-8 numbers or more, all this under your personal acceptance and using time that was being wasted doing nothing.

然后当天晚些时候， 你可能会想继续完成一些，到此刻你可能已经做完5到8项或者更多了，完成课业量是在你能 接受的范围内，并且都是利用那些很可能就被浪费掉的时间完成的。

youdao

Invest in developing techniques to recycle water so that nothing is wasted.

FORBES: Global Warming And Africa's Future: Part 2

Even if Skylon's tests are not wholly successful, the lessons from past development tell us that nothing is wasted - new knowledge will find applications.

BBC: For economic inspiration, look to space

Environmentalists dream of a world in which almost nothing is wasted.

ECONOMIST: The waste industry