Further, there are often conventions as to which symbols are used in which context. For example, \phi and \psi (with subscripts) are commonly used as a basis/f

Further, there are often conventions as to which symbols are used in which context. For example, \phi and \psi (with subscripts) are commonly used as a basis/frame for a vector space, \delta commonly represents a difference of two quantities, \rho is typically a density and \gamma is a decay rate. (These examples are fairly physics-specific, but other fields have similar conventions.) So if notation is well chosen, the reader doesn't need to remember as much unique notation as one might expect.