Tommy:
A fascinating yet, on the surface, pretty simple question: what makes a hole penal? While there are 300 pages waiting to be filled on the answer, I sense the abridged version comes down to this: when shaping up to play a shot that has 'penal' written all over it; it doesn't matter by how far you miss; if you miss the shot; the result (and penalty) is the same. There is no disadvantage by degrees - no slowly awakening realisation of the impending doom - no requirement to be playing the next shot from a worse position, namely, over a bunker to a tight pin, or of being 'blind' on the next shot. No! If you miss by twenty yards or by three inches, the result is the same.
Remember Phil M a few weeks ago when he carved his 72nd hole iron within 6 inches of getting wet. Had his ball just trickled in; well ... he may as well missed by fifty yards - no real difference to the score. Come to think of it, Phil's always been wet ... but that's a story for another day.
And surely, too, there are holes that would not be classified as 'penal' that have elements within that are, most assuredly, penal.
Contrast this philosophy with strategic design. Under this credo, a golfer will be hung out to dry by varying degrees, based on the inability to place the previous shot. But the hole is rarely 'lost'; it's just that fancy footwork is required from then on to extricate oneself from the mire.
Many of the best golf courses have holes, and layouts, that embody a combination of the strategic, penal and heroic.
Pine Valley, for one, has long been touted as an example of the penal school. Yet any one who has played it could think of many examples of strategic choices available, plus a healthy dose of 'heroic' opportunities to indulge. Naturally, it has holes that are wickedly penal in nature - and these have helped create the PV mystique - and other holes that are a combination of all three modes.
Royal Melbourne (West) ... it's just wall-to-wall strategy; your granny could play it - not well, mind you, but she'd finish. The old gal may even finish with the same ball.