At a certain level this would have been a case of plus ça change. Unless the death of a king prompted a drastic change in the day-to-day context (ie. a civil war began) then why would your life change significantly? You might, especially after 1209 and the Oath of Marlborough in England, have to travel to a regional power centre to publicly affirm your allegiance to the monarch and potentially his heir (which in and of itself is a counter-argument against ideas of a 'feudal society' - if the hierarchical chains of ascending loyalty functioned as you describe then why would these public affirmations exist? Surely the king needn't bother). Otherwise your obligations essentially remain the same, your social superior or landlord was still the same, and any extra exactions would be associated with the king's policy only in a very abstract manner. Peasants, burghers, and non-aristocratic groups were concerned chiefly with maintaining the social and legal conditions of their forebears (usually within a framework of who was reigning (ie. a return to conditions under Henry I might be desired in the reigns of John or Henry III). Peasant rebellions were very localised until well into the fourteenth-century when the economic connection was made clearer by a more centralised and codified English state.

ASOIAF is a rather barren sketch of a 'medieval' society. We know nothing about how these regional rulers pay their obligations, which would appear to be tributary rather than tax-based as these are 'vassalised' independent states rather than part of a wider realm. The Targaryens should have no 'right' to these territories. The loyalty, sealed by submission or alliance to the Targaryens, is not given a rationale for why it might carry over to Robert except that he was 'strong'. So the relations we observe are almost innately personal or familial (kith and kin) they are not 'feudal' in the sense of being land grants at the highest level. Within the realms feudo-vassalic relations can be observed but these tend to be reserved to the immediate households surrounding the rulers. Why the Boltons serve the Starks is unclear except for the hand wave that the Starks once defeated and secured the submission of the Boltons. The Manderleys have a more overt feudal relationship as they were invested with their seat by the Starks. We know nothing of the laws or customs which regulate the feudal relations in Westeros, how the economy is impacted by this, or even how the military is organised. Martin relies on an assumption that because this is a pseudo-medieval world whatever image of 'feudalism' the reader retains is sufficient to elide all the problems the actual events pose. In many ways Martin is attempting to have his cake and eat it by having concepts found in the fifteenth- through seventeenth-centuries held by people who act like they are living in the period 800-1100. There is no indication of a legal basis for the manner in which his society operates, nor for how it could function economically.

So yes, there are 'resources' that go into far greater depth than Martin's work because Martin is creating a fantasy - one which does not provide mechanistic explanations about how this society operates but instead hand waves legal and social complexities.