soft question - Acronyms and words as variables and in mathematical notation

I am unsure if this question is warranted.

Often mathematical symbols and objects are represented by a single character, e.g. variables are most often single characters like $x$, and often to describe a variable further we use an additional character in a subscript or a superscript, like $x_t$.

In physics people often choose intuitive letters to represent quantities as variables, for example, using $t$ for time or $v$ for velocity (starting character is used to make it more recognizable).

Of course this always isn't the case and I acknowledge that there are the cases of function names such as $\sin(x)$ or even objects like $\sup A$ and $\inf A$ for a set $A$.

However my question is what is the general opinion (concerning formal formatting) on using words, abbreviations, and acronyms as variable quantities in mathematical sentences.

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An example, we have that the revenue of a simple trade of a good is the quantity multiplied by the price. A few possible formats include:

1. $R = q\times p$


2. $\text{revenue} = \text{quantity} \times \text{price}$


3. $r = q_{\text{good}} \times p_{\text{good}}$

Perhaps #3 isn't so pretty with this simple formula, but if we take the mark-to-market formula of quantity times the difference in market price and trade price, we can get some other formats:

4. $\text{MTM} = q\times(p_{\text{market}} - p_{\text{trade}})$


5. $\text{MTM} = q\times (\text{MP} - \text{TP})$

and so forth.

Of course I see words and acronyms often in the equations from the softer sciences like economics where my example comes from, but I am sure this question applies to pure mathematics in some cases.

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I do not know which notation style we should tend towards these cases, especially if it was in the context of an academic paper.

Thanks for any opinions!