After working for years with a major plastering contractor I have learnt how to handle most situations.
When using task lighting on a plastered wall, it must be done with 3 lights. 1 at each end facing the centre and 1 face on to the wall. In UK this must be 110v lights. Not a battery light . Most plastering has to be to British standard this is what the customer is paying for. Not level 5 plastering.