It is most definitely 'easy' to burn 500+ calories in one session. One hour of squash burns 600+ calories. One hour of running burns 600 ish calories. One hour

It is most definitely 'easy' to burn 500+ calories in one session. One hour of squash burns 600+ calories. One hour of running burns 600 ish calories. One hour of cycling burns something like 400-500 calories. No citations for these figures, just going off memory Burning 500+ calories per session is definitely doable - if you are doing the right exercise in the right ways for the right duration.