Βεβαίως χρησιμοποιείται και για σωματική προσπάθεια (physical effort) και για πνευματική (mental effort). Αν δεν γίνεται σαφές από τα συμφραζόμενα για ποιον κόπο πρόκειται, το προσδιορίζουμε με επίθετο.
Φαίνεται και στα παραδείγματα του ODE, στη σημασία 1.2 με ορισμό:
mass noun Strenuous physical or mental exertion.
Ξεχώρισα τα παραδείγματα για πνευματική προσπάθεια:
‘The other things, like homework, require mental effort that they can see no result from and does not satisfy their needs.’
‘With a little more mental effort from wise people like yourselves, it could be improved.’
‘Computers supply answers at the press of a key, with no mental effort needed.’
‘He used to suffer from bad headaches and had to avoid all mental effort.’
‘He put huge physical and mental effort into achieving this goal, chasing his dream from his native Austria to London and on to California.’
‘She's also more easily distracted, so multitasking requires extra mental effort.’
‘It requires a lot of effort, talent and hard work to make programming that sustains both critical and popular acclaim.’
‘In the meantime I don't really feel much like blogging - it just requires too much mental effort at the moment.’
‘This is not so much due to time constraints as due to the fact that I don't feel like putting intense mental effort into it.’
‘It takes a great deal of mental effort to keep in mind the fact that whatever is happening is just plain fiction.’
‘It then took only a slight mental effort to isolate a moment within that time stream and to observe it.’
https://en.oxforddictionaries.com/definition/effort