One of my favorite features of this game is the ability to tweak and modify it. However, there is one thing that currently cannot be modified: Immigrant wave size.
Myself and many others on these forums have commented that we'd like much smaller waves; in the 2-5 per year range. I get overwhelmed when my humble 7 dwarf clan gets quadrupled in size and only continues to grow faster than I can find suitable jobs. Of course there are workarounds. Many people advocate separating and killing new immigrants by various nefarious means. Not only should this be unnecessary, but it can kill game immersion and verisimilitude. You can also modify the init to a lower population cap (I do this), but this also feels artificial. Once a fortress is started, I shouldn't have to keep tweaking game files to have fun with it. As I understand it, wave size is tied to created wealth, so you could slow down production to influence immigration, but this method is unreliable and constraining.
Smaller immigration waves have many advantages:
1. Greater challenge. You have to take care of your dwarfs and take measures to keep them safe from ambushes and other threats. Currently, if several dwarfs die, it's barely even inconvenient (maybe even preferable) as you'll get 20 more in an hour.
2. Babies and children are more meaningful. They become a viable source of population growth instead of useless mouths to feed.
3. The rewards of a high population are enhanced. It's more challenging and takes longer to grow a population, so getting the king, nobles, and a royal guard would be special and not be guaranteed.
I'm sure there are people who prefer the current large (or larger!) immigration waves. This is understandable, which is why I suggest making this an init adjustment. For players like me, we can have our smaller waves.