Well, if you are growing in soil, and assuming your tap ppm levels aren't an issue, it probably doesn't matter if you pH adjust as your tap probably (hopefully, hehe) has a pH between 6.5 and 7.5 which is close enough.
If you are growing in a soilless media or hydroponically, I think you should still pH adjust. If for no other reason than to reduce the possibility of shock on the plant. Some plants might want to herm if they are real sensistive to pH. This would be especially so for hydroponic flushing. Of course, we are only talking a week, so ehh, not really enough time unless the plants were on the edge anyway. It may matter less for soiless media. I grow a lot in coco coir, and two or three waterings in the last week of unadjusted pH isn't really going to make a difference. We are trying to get the plant to use up it's reserves, and it would take longer to move the media pH at the end of a run anyway I think.
I always pH adjust unless I am just too short on time or something and it is just going to be one watering or something. Starving the plant and forcing it to use it's reserves is easier on the plant than starving AND making it uncomfortable.
Small P