I did do the complete journey on one occasion, clockwise, of the Outer Circle 11 route (it was simply 11 in my time which ever direction it went).
My more frequent journeys on the Outer Circle were from Hall Green to Kings Heath and thence on the 27 to Stirchley. The 27 was a novelty to me as it was a BCT single deck route. I was used to Midland Red having single deckers - Acocks Green to Wythall in particular) but those on the BCT were rare. I noticed a pic of Sarehole Mill. Yes, that is the run down appearance I remember.
Addendum: I have since remembered that when at Bournville my first employer - after school - provided transport to and from the factory. I was only with them for six months and then I had to make my own travel arrangements to Bournville. This involved travel to Hall Green thence the 11 to Bournville and the reverse on my way home. As far as I recall my new employer, who was based in Edmund Street, paid my fares.
This lasted for almost a year when the family relocated to Devon.