Saved searches run on a schedule and top up your segments with new matches. Without a memory of what you have already rejected, they re-add the same unsuitable companies every week, and you re-review them every week.
Each saved search can now point at a rejected segment. Any company in that segment is excluded from future runs, permanently, at company level — so rejecting one contact at a company you have decided not to pursue also stops their colleagues arriving next month.
Pair it with the target segment: matches flow into one, your rejects accumulate in the other, and the search gets quieter and more accurate the longer it runs.