Where would you use runner block pulleys on sailboat?

Blocks are used in purchase systems on sailboats so sailors can better control the high amounts of load created by wind and sails. The way to make this difficult task simpler is by designing blocks that run freely and reduce the friction caused by sheets and lines in purchase systems. So what is the difference between ball bearing blocks and non-ball bearing blocks?

Ball bearing blocks are best for any system on your boat that does not see "static loads," or low-movement applications. Examples of a few recommended ball bearing block applications are main, jib, and spinnaker sheeting systems, traveler cars, and controls, and running rigging backstay runner blocks. Compared to non-ball bearing blocks, ball bearing blocks run freely allowing for increased safety and ease of use. Whether cruising or racing-the sailor can only exert a limited amount of power, so ease of operation and ability to release a line and let it run free is very important and is optimized with ball bearing blocks.

Non-ball bearing blocks are best fit for applications that hold high static loads and/or only change line direction, such as turning blocks, masts base blocks, deck organizers, halyard blocks, boom vangs, and reefing blocks. In these instances, a simpler, less expensive, non-ball bearing block makes the most sense.