In the context of industry demands, singers are required to produce higher singing efficiency. The research focuses on understanding and predicting singers' work efficiency controls, which are assessed using rework times (RwT) in recording studios. A comprehensive literature synthesis was conducted to identify nine critical factors combining advancements in both the acoustic field and recording practices. Each of these potential variables was measured while twenty individual singers independently performed the same original song. The musical passages (n=380) were analysed using the multiple linear regression method. The findings indicate that: 1. Rework times during the recording process are mainly predicted by intensity, singing duration, and rhythm consistency. 2. Intensity significantly affects rework times, acting as a negative factor. 3. The interaction between intensity and singing duration has a positive impact on rework times. We discussed the definition of intensity in vocal applications and how singers adjust recording efficiency.