I'm not sure that one approach is better than the other. I think that it depends upon the coach's personal preference and the athlete.
I recall hearing/reading stories about Vitaly Scherbo performing this vault and sometimes barely touching the table. The entire vault was performed as more of a RO double layout.
In contrast, I know of one prominent coach who simplifies the vault by describing it as nothing more than a "tumbling pass."
For me personally, I prefer to start with the RO BHS and build it upwards as opposed to starting high and coming down low. Assuming the RO BHS on the floor is pretty technically sound, I think that getting kids in lower to the table will be easier if you start them low and work them up to the table height. My goal is to establish that nice rhythm in with respect to the RO BHS. I want it to flow as smoothly as it would on the floor.
First off, I'd spend the time to make sure that they can effectively turn the RO over....ability to perform a RO that turns over to their back with mats at floor level from no more than maybe 1 or 2 steps and a hurdle. Ideally, I'd like them to be able to do it just a 1-step into an immediate hurdle...)
Then, I'd make sure that they can definitely turn it over onto a folded panel mat with proper body position and alignment from a standing position. (This really should be easy if they can satisfy the requirement listed above)
If they have a bad round-off and it doesn't look real promising, I'd probably scrap this vault in all honesty. With the table, most kids could probably get a piked Yurchenko with a poor RO, but they'll probably hit a plateau right there and not be able to progress much further unless they are just an "animal" of a tumbler/vaulter such that the motto of "technique is for the weak" applies whole-heartedly. But, for the average kid, I'd say that your time would be better spent developing a handspring or tsuk entry vault. Of course, if you're just trying to develop a back-up vault with minimal expectations for its future progress, this might be an alright option.
Once the RO is alright, then I'd start with a 3-step approach of performing RO BHS onto a springboard and 8 inch mat. I would concentrate on the turnover of the RO and the overall rhythm of the RO BHS. When this was to my satisfaction, then I'd add another 8 inch mat and gradually build it up and back the run up in a progression of 3-5-7-9 and eventually 11 or 13 steps.
Then, I'd move it over to the vault. Of course, take the vault down a little and pad it. But, I'd set up the matting to still allow the height to be at normal table height. While working the entry phase, you can simultaneously be working the post-flight portion of the vault. Here are some common drills:
double flipping on the trampoline
RO double tuck/pike/layout off of a springboard (even though I wouldn't approach the entry as such, I'm not opposed to this drill as a means of developing awareness)
standing tuck/pike/layout/layout 1/1, etc. off of the table
RO BHS up an incline/wedge/"cheese" with flipping off of the hands into a pit
and the list goes on....
As the entry phase of the vault becomes proficient, take the padding off of the vault and start doing timers to a mat stack. From there, it's flipping into the pit and gradually building the landing surface up to floor level and ideally...slightly above floor level for better preparation for competition surfaces.
All in all, I think that both methodologies are effective. Again, it's a matter of personal preference and what you think will work best for the particular athlete that you're working with.