I don't think that works ...? Or at least, not if having all trains going to Pier Head.
You have a northbound train at Brading, which has 32 min to to get to Pier Head and back to Brading - fine.
But the next train now has only 28 min to get to Pier Head and back - which doesn't work.
I think it only works if you turn alternate trains back at Esplanade, which is how it seems to be functioning now
You'd make a good timer, if I may be so bold. Have just had another look at this based on the timings in the WTT (section WJ) for 1987, which was 485/6 operated, and
nothing was planned to stop at Smallbrook jn in those days. But same (TT) applied during 483 days, which (I guess?) was the starting point for the 484 plan,
which also included stops at Smallbrook? I have no idea about that latter point, other than the following comments being a best (educated) guess on my part?
As things stand today, the crux of the TT problem is the passing point location that will (or not) allow a two train service to operate the entire 8 mile route from Ryde Pier to Shanklin, which is (now) single track, except (please correct me if I'm wrong) from South of Esplanade platform to Smallbrook Jn, and again a loop that encompasses Brading platforms (both).
Taking the WJ WTT timings in to account, and allowing for the passing point to be at Brading station only, assuming (in todays set up) the signalling allows an UP train to arrive and stop one minute before the down train arrives, and both could then depart at the same time in their respective directions (not just crossing on the double track section south of Brading as was the case with the 20/40 interval service in past times), then a 30 min interval service should still work, with a 7 min turn round at Shanklin, and a 5 min turn round at the Pier.
The 'BUT' in this scenario, is Smallbrook Junction, or should I say, the station stop dwell time at Smallbrook Junction, which from the IoWSR perspective is a must. This stop was not part of the timetable in 1987, Smallbrook still only being a passing point, but in todays world a Down train
stopping at Smallbrook will add (realistically/legally) in timings terms, add at least one minute in the down direction trains, which will then add an additional minute in to the departure time (from Brading) of UP trains, which after then stopping at Smallbrook themselves, will then be (at least) 2 mins later by the time they arrive at St.Johns, which by the time they then arrive at the Pier will be too late to meet the well established (legal) turn round times that have been long agreed by ASLEF and the TOC's, hence the timetable being too tight/legally unworkable at the Pier end.
So in essence, in the winter period, it may be possible for a two train/30 min interval service to operate with some reliability(?), but when station stops are required at Smallbrook Junction, then the service may need to be adjusted whereby only one train per hour runs to/from the Pier, and as such needs to be tail-doved to work with Wightlinks Ferries. Just thinking aloud here!