Real vs notated measures

This is discussed by Caplin, so he talks about it in the context of Classical music, however it can be expanded to any style.¹

Sometimes when looking at sheet music, you will see a theme be much longer than usual (e.g. 16 bars) or much shorter than usual (e.g. 4 bars). When playing at faster tempos, measures go by much more quickly, so 16 bars of notated music may "feel" like 8 bars of "real music".

This is obviously subjective but it's useful to consider when analyzing a score! You don't want to jump into the deep end of thinking it's a theme that doesn't fit into standard theme types such as the sentence or period, when it's really just one of those standard theme types but twice (or half) as long.