Time budget

A time budget names a quantity and a period: four hours of business development a week, one afternoon a month on people you have not spoken to. It says nothing about when. A time block says the opposite, that a named window belongs to a named kind of work. Most people write both kinds of sentence about their own week without noticing they have written two different instructions.

The difference is what each one does to the rest of the calendar. A block is bidirectional. Client work from nine to five means client work goes there and also that nothing else may, so the window leaves the pool of time everything else is competing for. A budget removes nothing from that pool. It is a total to reach by the end of the period, out of whatever is left once the fixed things are placed.

Which way an ambiguous sentence is read matters more than it sounds. Read a budget as a block and hours get fenced off that were never meant to be exclusive, so the week looks fuller than it is. Read a block as a budget and something else gets scheduled into a window that was already spoken for, which is the error people actually notice, because it puts two things at two o'clock.