Cutting-in like this could cause problems. One problem is picture framing, a visible difference between the cut-in and rolled areas. To minimize this use the following recommendations;
# Use very good quality paint.
# Minimize the width of the cut-in. 1-1/2 inches in enough.
# Roll very close to the other non-painted surfaces. Example- Walls cut-in to the ceiling, turn the roller horizontal and roll within 1/2 inch or closer then roll out the wall normally.
# Do not over apply the paint, dry roll. Apply at proper thickness without excessive rolling. Cut-in also need to be applied thickly.
# Use a good roller cover.
I suggest, if at all possible, complete entire rooms before moving into another area. This will slow down the progress but the results will be better.