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The Coffin-Manson relation makes cycles to failure inversely proportional to temperature swing raised to a power of typically 2-3 for solder. Reducing the swing from 100 to 70 degrees more than doubles life, which is why keeping a part warm is often better than cycling it cold.
Coffin-Manson
N = N_ref x (dT_ref / dT)^m, with m about 2-2.5 for eutectic solder
Because fatigue is driven by the strain from mismatched thermal expansion, and strain amplitude scales with the swing, not the absolute level.
For thermal fatigue, yes — fewer cycles means less damage. But leakage-driven wear-out and energy cost push the other way, so it is a genuine trade.