My personal impression is that 1939, 1940, 1941, and 1942 are all effectively "full-strength" NHL seasons, Im on the fence regarding 1943, and 1944, 1945 are essentially AHL equivalent or lower. The most important piece of evidence for this is the list of important names that are absent for 1944-1945, the presence of players that clearly seem to have been regarded as not NHL quality (ie Buzinski), and the rapid changes in the performance of some teams (ie see the war year Rangers who go from a good defensive team to one of the worst of all time in the span of 1940-1943).
Do we factor this in when considering major awards voting, team cup counts, and other all-time rankings?
Are there any reasonably founded doubts about the quality of the league immediately postwar, and in the next 5 or so years following it?
I think the number of players absent from the league from the previous season are as follows:
42/43 - 43 players
43/44- 30 players (73 total absent)
44/45 - five returned (68 total absent)
Certainly a significant figure. As for questioning individual awards, it's not unreasonable to wonder if there might have been better competition but cannot say with any amount of certainty as that gets too far into the arena of speculation.
Richard won goal titles in a dominant fashion after the war years, Lach won another scoring title in 47/48, Bentley won the Art Ross in 42/43 against many of the top scorers from the previous season (s). There are many more examples of players scoring within a reasonably acceptable range relative to their peers before, during, and after the war years to not automatically question anybody's scoring finishes.
As for wondering if raw point and goal totals from those years need context? They always do; the war years are no different.
As for wondering if the post war years need context? Hard to say. There really isn't an unusual turnover of the Top Ten scorers year to year starting in 40/41 thru to 48/49:
1941/42 - six new Top Ten scorers* (includes one player who missed some time but had a Top 5 PPG)
1942/43 - six new Top Ten scorers *
1943/44 - seven new Top Ten scorers*
1944/45 - eight new Top Ten scorers*
1945/46 - five new Top Ten scorers* (includes two from 42/43 Top Ten scorers)
1946/47 - five new Top Ten scorers* (includes four players from Top Tens before 42/43)
1947/48 - five new Top Ten scorer (includes two from the war years), two pre-war players stayed in Top Ten
1948/49 - seven new Top Ten scorers * (includes one from Top Tens before 42/43), one pre-war Top Ten player stayed in Top Ten
It seems like there are enough players staying in the Top Ten year to year that questioning the value of seasons is hardly obvious. Penciling in two or three missing players into the "war years" Top Tens seems reasonable.
Post-war saw some of the elite pre-war scorers return to the Top Ten and a handful of the elite war year scorers stay in the Top Ten. Not sure there is much evidence to say that the post war years were affected that much.