I had not considered building with a general contractor (GU). We build through individual contracts, but even in the Munich area, it is difficult to get offers. Usually, it still works out, and especially with small craft companies, you as a "private customer" have an advantage over GUs who mainly want to push the price down by politely asking.
We have often found that good companies are quite happy when you keep them up to date on the construction progress and allow some flexibility. They are always looking for construction sites where they can do small jobs (half a day) in between to avoid downtime despite having full order books. So far, almost all work in our projects has been completed ahead of the construction schedule. This only works if the tradespeople/workers on site know each other, meaning with regional companies.
And to get back to the topic here, finishing faster also saves money (rent, scaffolding, rental fees, frost protection, submersible pumps, etc...) and also a lot of nerves! We have calculated for ourselves that one month costs us about 1,500 euros extra.