Last week there had to be a maintenance call for my central heating. They did send me a time and date which didn't suit me, so I called them for another date. The only choice you have is between the morning or the afternoon. They said that they could not be any more specific. This means that you have to wait from 8am to 1pm or from 1pm to 6pm. You can't even use the bathroom in that timeframe as the person might be arriving then.
This maintenance call can be timed in minutes, as every cv in our neighborhood is the same. So, they can plan every call with an accuracy of 15 minutes. This means that they can easily tell me when the maintenance guy will be visiting my address.
It is clear that they are planning for themselves only and that there is disrespect for the customers. They simply don't care that you have to be at home and be available all morning or all afternoon.
While on the other hand it is quite easy to make a planning which serves both the customer and their own processes.
Who is the target of your planning?
GROW YOUR PEOPLE, GROW YOUR BUSINESS!