Measure twice and cut once .. works for timber but equally for plasterboard as it is a real mess if you have to repair incorrectly placed holes. I have therefore been very careful to measure and re-measure the fixings for the towel radiators.
The towel radiators are electric and switched for each bathroom on the outside … so we can use them when the need arises. Finding the wall studs and ensuring that they are aligning with the fixing brackets is a bit of a nightmare and not always successful so we have to use rawlplug expanding bolts to fix those brackets where the plasterboard is hollow.