Strong evidence

Strength, unlike size, does depend on training with heavy loads.

In practice

If the goal is a bigger one-rep max, some of your work has to be heavy and low-rep. Sets of fifteen build the muscle but not the skill of expressing force against a heavy bar.

Sources

• Schoenfeld BJ, Grgic J, Ogborn D, Krieger JW (2017). Strength and hypertrophy adaptations between low- vs. high-load resistance training: a systematic review and meta-analysis. Journal of Strength and Conditioning Research, 31(12):3508–3523. doi.org/10.1519/JSC.0000000000002200
• Currier BS, McLeod JC, Banfield L, Beyene J, Welton NJ, D'Souza AC, Keogh JAJ, Lin L, Coletta G, Yang A, Colenso-Semple LM, Lau KJ, Verboom A, Phillips SM (2023). Resistance training prescription for muscle strength and hypertrophy in healthy adults: a systematic review and Bayesian network meta-analysis. British Journal of Sports Medicine, 57:1211–1220. doi.org/10.1136/bjsports-2023-106807