Sorry, I do not think anyone can honestly answer your question, beacuse there is not single answer.
As you have found out, it is up to the specific manufacturer, and how many units that they feel they can produce profitibly before nobody wants anymore and suddenly their kits can be gotten dirt cheap at the discount houses.
Tamiya's buying public, like Revell, is so loyal, they can dump 1000's of just about anything on the market and dealers and wholesalers will gladly take them all.
On the other hand a company like DML has to be more careful, since they are not actually sekng to go "nose-to-nose" with Tamiya, but they aer seeking more of a niche, and such specialties tend to sell fewer units, but if you are careful, like Hasegawa, you can keep your price up by not releasing too many units at a time.
Sorry if I cannot make this moer clear, but that's the way it is in our profit-driven capitalistic society.
Tom
Tom T
“Failure is the opportunity to begin again more intelligently.”-Henry Ford
"Except in the fundamentals, think and let think"- J. Wesley
"I am impatient with stupidity, my people have learned to live without it"-Klaatu: "The Day the Earth Stood Still"
"All my men believe in God, they are ordered to"-Adolph Hitler