There is also a cost to future encoding of relevant information - I (roughly) recall an experiment with multiple rounds of lectures where participants took note

There is also a cost to future encoding of relevant information - I (roughly) recall an experiment with multiple rounds of lectures where participants took notes in a text document, and some were allowed to save the document while others weren't. Those who could save had worse recall of the information, however they had better recall of information given in the next round without note taking. Suggests to me there are limits to retention/encoding in a given period, and offloading retention frees resources for future encoding in that period. Also that study breaks are important :) Anecdotally, I often feel that learning thing 'pushes another out', especially if the things are learnt closely together. Similarly, I'm less likely to retain something if I know someone I'm with has that information - essentially indexing that information in social knowledge graphs. Pros and cons.