A question for skilled painters/decorators only.?

In my bathroom I have a really nice wood ceiling which I've had for a long while and wouldn't wish to get rid of. Previously the bathroom was fully tiled, few years ago we had a new fitted bathroom put in, walls plastered and only tiled the wet area. There is a 'shadow gap' round the edge of this ceiling and with the previous tiles the 'shadow gap' was painted a deep colour and wood ceiling only varnished, After the new bathroom the decorator did the 'shadow gap' same colour as the walls. At this point the paint was very neutral colours and walls and ceiling didn't vary much in colour. My huband is now repainting the bathroom in a pale aqua colour, ceiling off white and unsure if again we should continue the wall paint on to the 'shadow gap' or stop at top of wall? I would appreciate if this could only be answered by someone who is a skilled painter and familiar with what I talk of. Thank you.