KfW funding, how to determine if you will receive one?

Or, if the loan-to-value ratio is sufficiently good and one can also get good conditions on the free market, simply do everything oneself / have it done as makes sense and leave the KfW KfW. Instead of investing, for example, €15,000 in facade insulation that does not pay off during one’s lifetime, one can also pay a bit more interest and renovate the bathroom.