Maybe some of them, like in tight loops. But the most difficult code to understand for me is Matlab scripts written by physicists, naming variables a,b,c or i,ii,iii etc. Variables with longer lifespan should have more explicit names in my opinion.
Go sometimes gets a lot of flak for its style here (partially because it's sometimes misapplied) but I think it works pretty well: it's fine to use a short non-descript variable name like `a` if its uses only span a few (~5-10) lines (or other certain special cases like `i`, `j` for loop indexes), otherwise use longer descriptive names.