Commercial and residential work are often run from one calendar with one set of rules, and they do not behave the same way at all.
Why it matters
Residential routing is mostly a density problem: get the stops close together and the day works. Commercial routing is mostly a promise and continuity problem. The site can only be entered between certain hours, the paperwork has to be right for an inspection, and the same technician is expected because they know the building.
Mixing them without distinction means both lanes are planned by rules that only ever fitted one of them.
How you notice it slipping
Commercial visits are planned as if the arrival time were flexible. Documentation is completed after the fact. Commercial accounts change technicians as often as residential ones, which is where commercial contracts are usually lost.
What to do
Separate the two in planning even if they share a schedule: distinct service types, honest durations, access windows recorded as constraints rather than preferences, and a named owner per site. The rules are different because the business is different.