Who knows why it is recommended that Garam Masala is added nearer the end of cooking.
Garam Masala mixes vary. Essentially though there are two basic types.
1) Moghal Garam Masala
2) Garam Masala (Punjabi Garam Masala)
1) consists mainly of cardomom seeds, cinnamon, cloves and black peppers (and maybe a little nutmeg). This GM is harder to come by and best off making your own.
2) is 1) with fennel, bay leaf and large quantities of coriander and cumin added.
Commercial blends of GM also include salt, dry ginger, garlic and other seasonings and thickening agents such as poppy seeds.
Depending on the spice content of the "garam" masala and the particular recipe, it may be necessary to add the spices at the end (eg: the original Moghal GM uses "sweet spices" which do not need a lot of cooking), whereas a modern garam masala comprising fennel, ginger, garlic, cumin and coriander may need more cooking time.
Traditionally garam masala is used mostly with meat and to a lesser extent in poultry and rice dishes. It is rarely uses in fish or veg dishes because it's aroma is considered to be too strong for these.
So there really is no definite answer to your question Bobby.
Regards
SnS
