300 search terms to review and I lose concentration after about 40

There is, and it was built for exactly the problem you're describing. Search Terms Ninja shows one term at a time rather than a table. You decide - negative, keyword, or leave it - and it moves to the next. It sounds like a small difference and it is not: a table invites skimming, and one card at a time makes each decision discrete. Most people get through a backlog considerably faster that way while thinking about it more, which isn't the trade-off you would expect. It also remembers what you have already judged, which is the other half of your problem. If you leave something alone it drops out of the queue rather than reappearing tomorrow looking identical, so splitting the work across days actually works - you resume where you stopped instead of re-reading your own decisions. Two suggestions for a backlog that size: Do it in sittings of whatever your real attention span is. Yours is about 40, which is a perfectly normal number and better than most people's honest answer. Sort by cost first so the expensive decisions get your fresh attention. If concentration fails at term 200, you would rather it failed on the cheap tail.