I have no problem with an accelerated program. A couple of sessions per day should get a student soloed in a week. Three students to each instructor, a stick, worked well in the Army, especially when one of the the two not flying could observe from the jump seat.
Instrument is very specific and procedural. You can learn almost as much from the jump seat or back seat. Training weather, what is marginal VFR, when VFR is safer than IFR, etc is more time consuming and difficult.
The flight test creators want to make private and commercial as similar to the instrument as possible, which makes it also very specific and procedural. Many of the various VFR missions simply are not specific and procedural, thus quite a bit of disconnect with reality. It makes acceleration easier if the intent is to train for passenger transport or corporate flying only.
Missionary, Mountain, Ag, Patrick's Backcountry, Kevin's Backcountry, and OJT programs are helpful but rare. Old guys like me who teach what they think is important is also rare. Far more pilots fly non passenger transport or non corporate.
High is safer and less interesting. Computers do it quite well. Low requires a different orientation. Computers don't do it well because the tactical situation is really, really fluid where horizontal clearance is more important than vertical clearance, ie altitude.
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