The straw that broke the camel's back
It can take one additional small thing to push something over the edge.
There is an idiom "the straw that broke the camel's back" which, according to Wikipedia, describes
a minor or routine action that causes an unpredictably large and sudden reaction due of the cumulative effect of other small actions.
Seth Godin recently wrote an article about "x1000" where he gives examples of things which when they happen a few times are manageable but when they happen one thousand times causes pain. He writes about the volume of spam phone calls and also a more extreme one in the form of climate change:
One freakish storm is something many economies and communities have a chance to recover from. But 1,000 days of weird weather is more than we can handle.
Another article writes about the concept of "silent sacking". They propose that a company can change the conditions of work of someone to make them so unattractive that it effectively forces them to quit. They may be able to cope with a few changes but the accumulation of changes creates an environment they can no longer tolerate. (FYI I have no idea if that is happening at Amazon as they claim - I am just covering the concept).
We have seen recently on our project where a number of small changes had a cumulative effect on the performance. It was not one thing but a series of unrelated changes, each impacting the performance a little that added up to a noticeable change. It took one of our engineers a week to work through them all and refactor them to restore performance.
We can see it in children. They learn how to nudge their parents into submission by repeating actions or requests until the parent can take no more and either snaps or gives in. The single action or request has little effect but the repetition has an impact.
It doesn't always have to be negative. Maybe we can make the world a better place by doing small actions that have a cumulative effect. Maybe it would then become the "straw that fixed the camel's back"?