Not at all. Here's a sample from 1987:
"A" - R27s, R38s, R44s
"B-Bway" - R16s, R27/30s, R32s, R40Ss, R42s, R68s
"D-Bway & Q" - R27/30s, R32s, R40Ss, R42s R68s
"B-CPW" - R42s
"D-Conc" - R40Ms, R42s
"J", "L", "M" - R16s, R27/30s, R42s
"R" - R16s, R27/30s, R32s, R40Ss, R42s (this was before 5/87 while still going to Astoria)
The IRT in 1983 (pre-R62/R62As):
"1" - R14s, R15s, R21s, R22s, R29s, R36WF
"2" - R22s, R26s, R28s, R29s, R33s
"3" - R14s, R22s, R33s, R36WFs, R36MLs
"4" - R17s, R21s, R33s (only 10 cars)
"5" - The same as the "2", plus R21s
"6" - R17s, R22s, R26s, R28s, R33s
"7" - R17s, R33Ss, R36WFs, R36MLs
Furthermore, with the IRT, you can find all of these consists mixed up in the same train. For example, with the "3", it was common to find all five classes of cars that I just mentioned in one train.