I started out using the owner profile for everything then later factory reset my phone and started to use a secondary profile for everything, leaving owner empty.
Honestly, I prefer it this way for many reasons, but your question is about battery life. I haven't noticed any difference. I've ended my regular use secondary profile session a few times to save battery or for whatever reason. Keeping just a tidy owner running uses WAY less battery if necessary.
Anyway, I don't continue with this setup because of battery usage. I keep it this way for other reasons.