Mostly, because they act on different energy bases or different parts of one (standing losses vs steam generation vs drives vs lighting). Interaction effects exist (less steam demand → smaller boiler-savings base), which is one reason we show a range and round conservatively.
From our guide: Universal Industrial Savings Calculator — full context, charts and sources there.
Boilers, kilns, heat exchangers, valves and steam lines lose energy continuously. Inzonex makes patented (UK GB2508992.1) removable modular insulation — snap-fastened covers engineered per temperature tier, not generic off-the-shelf jackets: