The next war will probably start over voltage/potential being written as U, V, or even E.
Things get very complicated if you try to bridge between subject areas. For example, is \$U\$ voltage or internal energy? Is \$V\$ voltage or volume? Is \$E\$ emf or energy? Is \$P\$ power or pressure? Is \$Q\$ charge or heat flow or volumetric flow?
When writing formal memos, I often waste time thinking about which letter to use for an added variable because of the connotations with other variables. A generic variable could be A, but that sounds like area, and so on down the alphabet. Bad enough confusing E = voltage gradient = electric field with E = energy, ignoring EMF = electromotive force that sounds like the electromagnetic field that makes cellphones dangerous.
I'm probably a s bad as anyone, but we all have aspects of notational ambiguity that grinds our gears.
If I see EMF written or hear it mentioned I also always ask for clarification before engaging because the new science nutters love spouting about its harmful effects.
The one that gets the blood pressure rising is possibly the least important, not even as part of an equation... the capitalisation of the letter k, as in Kg.
It causes another possible aversion to the use of LT Spice that Bob Pease perhaps didn't pick up.
Old schematics are fun too! resistances for instance marked 500M ... M to denote 10³ rather than 10⁶ I assume for mille or millia...
The list is long and often fun to negotiate.