I'm doing a no-boss run mostly because I hate raids and don't like spamming stopevent command, it's currently day 97, I'm starting silver age and I think Eikthyr has sent his necks and boars at me maybe three times so far. No other raids but as far as I know you need to kill some bosses to enable certain raids (like Elder + troll -> troll raids). I remember having much more frequent events when playing in the past both alone and multiplayer, but I don't know if it's just randomness or if something has really been changed.