The sweet spot is personal. Two people with identical measurements might like slightly different positions. For example, some people like riding down on the drops, with their back a little arched, others like a more upright position. In my case, as I have aged I prefer a more upright position. So even the same person can change over time. While doing the exercise of taking a given geometry and seeing if your measurements sort of fit is useful, riding the bike is needed for that extra subjective factor.

Many people go in the opposite direction when they become experienced riders, taking their measurements and style as a given and asking for a bike that fits them rather than trying to fit something off-the-rack. That's why we sort of half-joke about the motion capture suit. It actually makes sense!