What I mean is that the data for a particular user is worthless after 90 days (really more like 30). Aggregated data is useful for building models, but individ

What I mean is that the data for a particular user is worthless after 90 days (really more like 30). Aggregated data is useful for building models, but individual user data is not useful for targeting that particular user. For example, suppose you are ranking search results for Alice. It may be beneficial to include old data in your language model or indexing models. However, it would likely not be beneficial to include Alice-specific features that go back more than 30-90 days. Such features include counters for her actions (clicks, queries, scroll), embeddings of her activity, etc. On the other hand, site and query specific features would likely be useful for years.