I have seen 3 major ways of subdividing the quarter notes in 5/4. 1 is treating it as a simple meter and 2 others treat it as an irregular compound(or technically speaking, complex) meter. I have seen these interpretations in 2 main contexts, conducting an orchestra and music theory. I myself, when I see 5/4 always treat it the same way regardless of tempo. Of course, I can oblige by composers who used 5/4 as 2+3 or 3+2 by placing dynamic accents on the first note of each 2 or 3 note subdivision. But in my own compositions, I don't abide by the 2+3 or 3+2 that everybody else does when I use 5/4. I only use the irregular compound that everybody else uses for 7/4 and higher prime time signatures.
Simple Quintuple Meter
This is the interpretation I use in my own compositions when I use 5/4 is that 5/4 is a Simple Quintuple Meter. I mean, it makes sense right? 5 beats per bar, that is pretty easy to count, and isn't it ease of counting that makes 2/4, 3/4, and 4/4 all simple meters, even though in theory, the 4/4 could be subdivided into 2+2? 6/4 is when you really start needing to subdivide the bars into larger beats than the time signature. But 5/4 is easy to count as individual quarter notes, no need for subdivision.
1 2 3 4 5 | 1 2 3 4 5 | 1 2 3 4 5 | 1 2 3 4 5 |
This here is an example of a conducting gesture in 5 beats:
I see this used mainly for slow movements in 5/4 because at faster tempos it is hard to conduct in this 5 beat pattern. So for fast movements in 5/4, conductors generally will use a pattern of 2/4 3/4 2/4 3/4 or 3/4 2/4 3/4 2/4 depending on which beats the composer wanted to be accented beats. But for a solo pianist like me, counting in groups of 5 at a fast tempo is no problem.
Irregular Compound Meter(or complex meter)
This is the 2+3 and 3+2 that I have mentioned before. This has its merits, mainly for conductors, because the conductor doesn't have to use a 5 beat pattern which is difficult to do at fast tempos. But, if 5/4 is treated as an irregular compound meter, how would you know which accent pattern the composer wanted, whether it was 2+3 or 3+2? What if there are a lot of short notes in a given bar, making it hard to see the accents? Some composers have left the accents ambiguous, some have emphasized the accented beats with dynamic accents to make it clear, and others decomposed the 5/4 into 2/4 + 3/4 and used multiple time signature changes or a dual time signature to make it absolutely clear what interpretation the composer was going for.
So, given that 5/4 can be interpreted either as a Simple Quintuple Meter or as an Irregular Compound Meter and that each one has its merits, how should 5/4 be classified? As a simple meter? As an irregular compound meter?