Glad you liked it!
The goal was to never be too far away from the next upgrade, but it's hard to keep all the numbers balanced to make that always be the case. Definitely the 'zen' of just picking the berries or watching your pickers work is meant to be part of the experience so the downtime between upgrades is still engaging.
Re: unpredictability, originally I was gonna make the sun move around more randomly, but decided to make it predictable precisely so you could be intentional about placing the buildings for maximum effect.