as i understand it, market profile originally used time essentially as a proxy for price, since volume at price data was not readily available realtime.
it is a pretty decent proxy.
but
in my experience volume at price (segmented over time) is more useful, especially when taking into account the 24 hr market action. market can stay in a narrow price range for hours in globex session with very little volume. clearly, that does not show the kind of price acceptance as when thousands of shares are crossing hands at the same level during the day.
i constantly compare my volume
POC and time
POC to try to discern the differences during different day types and which is more reliable.
now that we have realtime access to tick data, i think volume at price is much more useful. this goes along with my general understanding of pit action, wherein time is not what matters nearly as much as volume.