Two different clocks run on a plastering job and confusing them causes most of the scheduling problems homeowners run into.
Time on site
MyJobQuote's timings are a fair guide: a small room in one day, a medium room in one to two days, a large room in two to three, and a patch repair in two to four hours.
Those assume a skim over a sound surface. Add a day or more if the old plaster has to come off, because hacking off, clearing debris and dubbing out the wall to a level surface is genuinely a separate stage of work.
Add time for a ceiling as well. A room and ceiling together is usually a day longer than the walls alone.
Time to dry
This is the clock people forget. Finishing on site is not the end of the job, it is the start of the wait.
A skim needs three to seven days to dry in a warm, ventilated room, and the safe interval before painting is up to four weeks. Backing plaster on solid brick takes longer still.
So a double bedroom might be one to two days of a plasterer being in your house and then anywhere from a week to a month before you can decorate it. Plan the decorator's start date after the plaster is dry, not after the plasterer leaves.
Why the work cannot be spread out
Plaster sets on a chemical timetable of roughly ninety minutes to two hours from mixing to final trowel. Within that window it has to be applied, flattened, and polished through several passes.
The consequence is that a plasterer cannot stop halfway across a wall and resume tomorrow. The join would show permanently as a line visible in raking light. Each continuous surface has to be completed in one session.
This is why plasterers work long, uninterrupted days and why rescheduling mid-job is difficult. If they say they need to finish the room today, that is a physical constraint rather than a preference.
Sequencing around other trades
Plastering sits at a specific point in a renovation and getting it wrong is expensive.
It comes after first fix electrics and plumbing, so cables and pipes are chased into the walls and covered. It comes after any structural work, new openings or damp treatment. It comes before second fix, before flooring, and before decorating.
Booking a plasterer before the electrician has finished chasing out means either a wasted visit or a wall that has to be cut open again.
Living with it
Expect the room to be unusable for the duration and messy afterwards regardless of precautions. Plaster dust travels, so seal doorways if the rest of the house is finished.
You will also want windows open for days afterwards, which is worth thinking about in winter. A room drying properly is a cold room, and rushing that with a heater against the wall causes shrinkage cracks.
Build the drying time into your plans from the start. It is the single most common reason a decorating date slips.