When I completed my initial IR training back in 1984 I asked my trainer, who was a well known and respected pilot this exact same question. I got a 5 minute chat and that was it. I had under 1000hrs at the time. At no time was this covered during my training, and by the look of this thread nor does it appear to be the case today.
Some will say use common sense, however it shouldn't be left up to that, this is something that should be well covered, including your options in the event of an engine out. Above 5700kg this is all covered by 20.7.1b (or whatever!) and the operator is required to cover all the likely en-route scenarios etc. Light twins etc aren't and are usually flown by pilots with minimal experience and it shouldn't be left to luck or common sense, but covered by good briefings on how to best plan for these situations etc.
I recognise a lot of posters here (not personally) who generally have >5700kg jet or heavy RPT turbo-prop time and have their experience to fall back on. Most new twin IFR drivers don't.