My understanding is it tries to emphasize one other dimension of markets that is less looked at: time. On a standard chart we do see volume, price, time, but it's much harder to identify visually what is the average amount of time spent in given areas vs. a market profile chart. Although that knowledge still doesn't really help me work out why it's not really touched by any successful stock traders.
I assume by 'fixed time' you mean intervals for the profile set by the market open/closes? And what's 'volume segmentation'? And 'time segmentation'?
'Fixed time' could be any time segmentation. It could be the entire day's information (which is the traditional method) It could be 5 day's cumulative data or it could be that you build a separate profile for each hour or even each bar - https://www.elitetrader.com/et/threads/what-is-inside-your-5-minute-candle.328126/ The images below are of 24 hour profiles and 100,000 'volume segmentation' profiles - a new profile is built after 100k contracts are traded.
The concept of time at price is probably more important than volume at price TBH. The more time spent at price, the more acceptance of that price valuation. The less time spent at a price, then obviously the market perceives that price to either be under or over valued. MP is essentially a vertical histogram - that in itself isn't especially novel, but I would submit that the concept of market "control areas" is unique and curious. To understand MP, you need to do a very deep dive into "control areas".
In the OG Market Profile, the "volume" was actually for price prints - not traded contract volume. There were CBoT employees in each open outcry Pit that recorded time and sales as best as they could. The concepts of a market accepting or rejecting a valuation and the behaviors of price discovery such as "control areas" are as relevant today as they were 40 years ago.
What would be your reasoning behind segmenting by volume? And on what reasoned basis would you pick one quantity of volume over another?
Just thinking about this fairly superficially and quickly, that makes sense to me. You'd expect a market with lots of active participants to respond quickly—a measure of time—to a perceived mispricing. That seems to be the essential aspect rather than volume since a large quantity of volume could occur for many other reasons in addition other than responding to a perceived mis-pricing, e.g., a market open/close forcing orders, hedging, rolls (can you think of any others?) Thoughts bone?
I've been doing some reading lately on the concepts behind this charting method (profile) and the only meaning of 'price control' I seemed to find essentially equated to a defined price range. Or is it something else?
You can test specific quantities of volume and measure the range variances/volatility they create. Different quantities of volume are for different levels of granularity.