Hey, thanks for the reply! Really happy to hear that you're still working on it.
I 100% agree that it would be bad to start at the first queen wave with a ton of souls, and it would also be bad to place multiple defences before the wave start. With that said, starting at wave 10 specifically would discourage me from building the same layout every time. I start with a basic symmetrical layout of 8 eyes inside a ring of 8 skulls, so I'm not making any building decisions or in any situations where panic building leads to non-optimal placement until about wave 14 when the rings are done and it's time to defend against pirates. As long as mobs still start spawning as soon as you place the first defence, starting at wave 10 would mean having to build very quickly to defend against bandits, knights and vikings, you'd have only enough souls to build 6 skulls and 6 eyes or equivalent - it would be hectic, but it also opens up layout options, since player is no longer restricted by the build part unlock order and the incremental build costs which usually have me building eyes and skulls in pairs until I have to start thinking about pirates.