Growing in pots certainly has its disadvantageous. Warm soil is very stressful to most lilies.
Of course, many if not most of those are not really dead, Anthony, just dead for the year above the surface. I've had
Lilium distichum die back in early June, but still with a healthy bulb beneath. One would think that with lilies, only bulb depletion occurs in early spring while it sprints growth, but that's not the case.
(Here comes my underground structure addiction again
)
New scales are growing in spring, too. Also take note, that actual
bulb growth is not completely dependent on photosynthesis that happens above the surface. When a martagon bulb skips a season of above ground growth, the bulb still gets larger, although in most cases not as large as if the plant had actually grown leaves.