And I say if it makes you feel good, do it. I don't see any harm shortening the intervals. I'm just relaying my own experience. Off of oil and onto brake fluid. I think BMW's brake fluid intervals is way to long. Too many people ignore brake fluid.
I agree 100%.... I pull my wheels twice a year to give them a thorough cleaning and re anti seize the hub flanges. I add a brake flush to this process every other time (12 months). The fluid comes out tea colored until the fresh fluid makes it through the system. I'm also vehemently against pushing old fluid out of the calipers and back up into the system when changing brakes. I always flush first then change pads.
In My personal experience,( I've owned 5 BMW cars and 2 motorcycles) I always used Castrol GTX oil and adjusted weights based on temperature as stated in the older manuals. I would pull the dip stick and see what it looked like. If it was getting dirty or discolored, I scheduled a change in the near future . My first new BMW was a 83 320i, I put just over 400k mi on that car with minimal issues. I purchased a used 533i with 150k on the clock, and drove it for 200k more. My 73' Bavaria came with synthetic oil , Mobil 1. I was not impressed with the M1, but I stuck with it. Now with the 99' 323 I started running Castrol Syntec with no issues for 225k. Now I have switched again to Lubro Moly with My 07' 525xi e60. The bike still gets Castrol GTX, 60k on My 04' R1150R and no issues. Moral of the story, use a quality oil and keep a vigilant maintenance schedule and your motor will last for a good long time.