With OKRs, it’s important to set them high enough. Getting 100% should be a near-impossible feat that only a few teams accomplish.
OKRs should be reviewed weekly to avoid discovering that you have no results at the end of the quarter. However, and this is important: you should not grade success based on your Objectives. The grading goes on at the Key Results level. And KRs must always be measurable, and you need to figure out that criteria when setting them.