All the rides I have been on have used paint except for one. My most recent ride was a four day tour. Apparently parts of the route were popular for cycling events so there were other people's markings on the road. Our ride organizers knew that and used a different color plus the event name (BAAM) painted as well as the arrows.

The route was well marked, with the arrows both ahead of time and at the turns. Also, I understand that there were "missed turn" markings after the actual turn location.

The one ride that did not have road paint used signs. It was very, very hard to follow the course and many people made wrong turns.