On my ST I changed oil and filter twice a year, regardless of mileage, Around August 1 and at the end of the season oil and filter once more. Used Rotella T4, around $3.5 / L and the bike needed 3.4 L with a filter change. Usually did 6,000 to 10,000 km a year.
Have had the Tracer 2 seasons, higher stressed engine than the ST, still doing the the midseason change, but filter only in the fall. Motul 5100 semi synthetic. Filter is $20 locally, but Motul 5100 is not cheap, 4L jugs on sale are $63 ($15.75 / L ) and the bike needs about 2.5 L per change. Each oil change with filter is about $60 vs the ST cost of $25 with a U.S. purchased filter.
I just purchased a case of 12 L of Amsoil fully synthetic at $18.50 L, not cheap stuff.
Tracer manual says change oil at 7,000 km or every 6 months. Filter to be changed every 2nd oil change. Co-incidentally, last 2 years did 14,000 km total, or 7,000 km a season.
So, in my mind, with my annual mileage, is the mid season change really necessary, in particular now that I'm using fully synthetic? Probably not, but even with the more expensive Amsoil this is a <$50 issue and given what I spend annually on the bike and accessories this is chump change, so I'll probably keep on with the 2 changes per season.