In a recent UK TV programme it was implied that planting bulbs deeper
than "normal" discouraged bulbs from increasing by side bulblets, and
consequently gave larger flowers and continuing flowering in subsequent
years. In this case large flowered tulip hybrids were the example. The
commentary I think said "deeper planting, equals cooler bulbs, larger
flowers, longer bulb life", though presumably less bulb increase.
Is this "cooler bulbs point" a valid argument for bulbs like tulips, or
indeed bulbs in general?

An aspect of planting that I
overlooked, to my detriment, for many years is the depth that one plants
mature bulbs and corms. Consider the normal growth cycle from seed. The
plant pulls itself down to the optimum level before producing flowers. So
when planting mature or near-mature bulbs/corms, err on the shallow side
rather than too deep. Too deep and you will produce spindly plants that
will finally give up the ghost. On the other hand, planted too shallow,
they might require a little more time to flowering properly. Also don't be
shy to plant your bulbs/corms grouped together ie. in the middle of the
container. I am convinced there is a symbiotic influence. Certain corms
such as Lapeirousia's, Romulea's and Hesperantha's are bell-shaped with a
flat bottom, plant these at an angle to assist their movement down to the
optimum level (I always make a note of the depth of existing bulbs/corms
when re-potting).