importance of workings F5 and where to put them

Hi
How important is showing the workings if the final answer is correct? E.g. when I compare series of data and I use ratios, indexes etc. do I have to show the workings to get full marks as in ACCA’s reference answers even if I answer correctly?
And if I have to show the workings, then do they have to be so nicely below the answer as in reference answers? Or may I intertwine them into the answer that would be faster for me to write e.g. writing them in brackets? I think one must be a psychic to envisage how much gap they should leave for the answer to fit before the workings start.
Regards
Andy