historically have pre-seed funds performed better by keeping resrvers for follow-on or by increasing the number of companies they invest in

Most small funds can't have reserves. Reserves are viable around the $20m range. This is because, in many cases, just maintaining pro-rata in some of the winners can cost millions of dollars. So it's just not really viable for funds <$10m and it's a sub-optimal strategy for Fund 1s. With Fund 1, you need to get it done, and move on to Fund 2 quick so that you're no longer a new manager.