There was no help given. Only thing you gave was a condescending attitude and some non-scientific opinion. Here is what two Audiologists have to say.
Question: Do ear canal sizes/shapes continuously change, requiring reshells every few years? If so, is there an explanation as to why? Many people need refits with customs; what have you seen to be the reasons? Something wrong with the initial impression, something during the custom making process, etc.
Answer, Audiologist A: "The ear canals and outer ear normally don't change dimensions frequently but over several years the fit does change. It is usually due to, in part, a significant change in weight; loss of weight creates a looser fit. Our tissues change in their firmness over time too so the monitors can loosen up. As I mentioned in an earlier email. silicone shrinks over time, but if the monitor is made of acrylic as many are, the above issues can change the fit. The original impression can also be a significant factor in the long/short term longevity of the fit. If the original impression material shrank during the curing process the monitors will inherently have slit leaks. Silicone shrinks less than the older liquid/powder impression material that silicone replaced. Some individuals may still use the older impression materials. It is also possible that use of the bite block results in a slightly tighter fit in the canal when the jaw is closed. As I had said earlier, I don't use bite blocks in my practice except for the impressions I take for Ultimate Ears. For hearing aid fittings it doesn't seem to make a difference. But music is wide band and in conjunction with normal hearing a small slit leak can surface with a noticeable loss of bass; hence the need for a remake for a tighter fit. It is also possible that the manufacturing process that results in the custom shell, having several steps that induce slight differences from the original impression, might result in a less than perfect fit. There really are so many variables as you can see."
Answer, Audiologist B: "Yes, our ears do change a little, but not enough for a reshell every 2-3 years. To be honest it differs with everyone and there isn't really a
set time you can put on it. Realistically, your customs should last you at least 5 years and might still be good in 10 years. The only time I would recommend getting a reshell is if the current shell is uncomfortable or doesn't fit. The ears do change with weight gain/loss, too."