Getting training for NAVRES MARS officers on a continuous basis fell apart in 2004. I was staff at NOTC, although I left six months ago I'll let you know what had been set up (although NAVRES HQ is constantly asking for changes).
* in 2004 NAVRES HQ wanted to get all of the training done in 3 consecutive summers, but the number of weeks of training (54) exceeds the number of weeks in 3 summer (48 in total)
* in order to maintain a Total Force training standard - i.e., that BOTC, NETPO, MARS III and MARS IV have the SAME course standard and training delivery, the only way to get three summers of training was to move some of the material to be instructed at the Naval Reserve Divisions
* all Regular Force officers complete the full BOTC before arriving at NOTC, and the full NETPO at NOTC, so there is no issue of scheduling the follow-on MARS III, which was generally in early September
* there was some consideration given to finishing off BOTC and NETPO for those that wanted to, but two factors stopped that: first, was that there were not enough potential candidates to make running the "continuation courses" viable; second, was that there was not enough time in the fall to get the BOTC/NETPO completed and start the MARS III with the Regular Force serial - and there was not enough resources to run two separate MARS III courses (given that there are other courses running, as well)
* so, regrettably NAVRES officers get stuck into: summer 1-BOTC/NETPO, fall & winter 1-finish BOTC/NETPO, summer 2-MARS III, summer 3-MARS IV. There is the possibility that 'misshardie' mentioned, of doing MARS III and IV consecutively after summer 2. NOTC's policy (when I was there) was that candidates, regardless of component, were loaded on the courses as space was available. It was a dialogue between DMTE (Ottawa - for Reg Force), and NAVRES HQ about how many of each component went into a course (contrary to conspiracy theory and typical NOTC bashing, NOTC was not the unit that decided the priority). Typically when I was there out of a course of 20 spaces for MARS IV, about 1/3 would be NAVRES folks, based mostly on their availability but admittedly some did not get the course when they wanted it
Oh, and just to be clear, no matter what anybody says this is what the NAVRES HQ wanted!! They knew it would prevent people from doing their training straight through.
Many years ago there were differences, and the NAVRES training was a weaker standard (when I did training, a looong time ago, the NAVRES students didn't even go to NOTC!)However, to correct 'misshardie', as I mentioned above, when I left NOTC there was no distinction between Reg and Res MARS training, and was that way since around 2000 unofficially and 2001 officially. There was a small exception in NETPO, which was about six or eight lectures that were specific to HALIFAX class ships, replaced with lectures specific to KINGSTON class ships, and the Reg Force did a little bit more on Force Protection etc. But for MARS III and IV, the courses were the same: the same material, the same standards, although the NAVRES "summer" modules created a difference in timing and some delivery methods.
The idea of Total Force training, laid out as part of the VCDS's white paper some years ago, was championed by NOTC. It was NOTC that drove the programme to one standard for all MARS officers. In fact, some very senior people in NAVRES did NOT want it to happen (and still fight against it). NOTC's viewpoint was that the basic maritime skills required of ALL those who stand a bridge watch, were the same. Depending on the class of ship the person goes to after training determines the types of intermediate and advanced training the person receives.
It is unfortunate that NAVRES continues to fight the common standard, but that's empire building for you.
Finally, in terms of finding out exactly what is happening, my advice is to contact NOTC directly. My experience as NOTC staff showed me something very clearly: too many "experienced" MARS officers in the NRDs did not know what was going on because they were describing their training from three, five or even ten years ago and assuming it was the same; and that even people in NAVRES HQ did not seem to know, or would not give full information. Even my notes may be wrong as I left NOTC six months ago and it's possible that there is going to be a separation of the standards. So, as I mentioned, contact NOTC directly: get in touch with the Assistant MARS Department Head, that's the person who coordinates all of this stuff for the MARS department.
A long post, but one that I hope will help.
I am not aware of any reservists who got on the Reg MARS III course this fall... there is no fall RES course. If you are lucky enough to get on the course, they will make arrangements to expedite the DL package to finish NETP-O, so I wouldn't worry too much about that. There was no BOTC DL package this year. 
