Shallow may or may not mean stress. In heavier clay soils, a bulb's natural depth will be more shallow than in a sandy soil. In fact, in my previous discussion, the bulbs were quite deep (5-6 inches) for their size. In fact, I initially wondered if that was the reason for them being so small. But further inspection revealed that they were not dwindling in size, rather they were small bulbs dividing into even smaller bulbs.
Regarding the bulb "shrinking and growing" supposition over a growing season, that is not usually the case with lilies. The "depletion" of food from the bulb during the early season growth cycle doesn't seem to have much of an effect on lily bulb size. I suspect that while certain needed nutrients are removed, it does not really impact the empirical structure of the bulb itself, merely its internal make up.
In this pic of a
Lilium sulphureum bulb dug in the fall, one can clearly see the part of the bulb that is the current season's growth, with the loose looking outer scales from the previous year that are not shrunken at all. Also in the photo, notice the remnants of scales from what I assume to be the year before that. Had these senesced earlier in the season during stem or flower growth, they would have decomposed to nothing in the moist clay soil the bulb grew in. I contend that their demise coincided with the onset of serious bulb production and storage priority that begins in earnest as flowers wain.
The Lilium genus is quite diverse, and as in most cases with almost any botanical theory, there are no unbroken rules. There very well could be some that support the early season shrinking theory, but I don't think it is the norm.
