A larger pack can be convenient for several rooms, but the useful quantity depends on how the work is organised. Count the covers you need at the same time before deciding how many sheets to buy.
Make a covering list
List the items that will remain in each room. Note the measured span of every large item and whether it needs one sheet or several. Include awkward joins and any cover that must stay in place while the next room is prepared.
Distinguish simultaneous work from sequential work. If every room is being decorated together, all the covers may be needed at once. If you work room by room, reuse may be possible only where the product permits it and the sheet remains suitable.
Do not base the plan on guaranteed reuse of a sheet you have not inspected after its first job.
Keep the pack comparison consistent
Compare packs within the same intended-use family and with the same sheet dimensions. Six smaller sheets and three larger sheets are different choices even if the total area looks similar.
Read “pack” carefully in the basket. Buying two ten-packs normally means two retail units containing twenty sheets, rather than two individual sheets. Check the line description before completing the order.
Compare the whole purchase
A per-sheet price can make a pack comparison easier, but delivery charges and the number you will actually use also matter. Avoid treating unused sheets as a saving simply because the unit price is lower.
Keep spare unopened sheets with their product information. That gives you a known reference for the next stage and avoids having to guess which protection level an unlabelled bundle belongs to.
A good pack choice covers the planned tasks with a sensible allowance. It should follow the job list, rather than a headline quantity alone.