The reason why people use Heka's is that with it you can free up other slots. With it you can cap +potency -Cast time and -enmity at the same time, it makes you not have to waste for instance your hands slot on potency which then allows you to use theophany+1 for some minus enmity and plus healing magic (just one example there are other things you can do).

You should not idle in Heka though. You already have to sacrifice the safety of ilvl on hands/legs/feet/ for refresh (serpente and nares) with heka you then complete that with all 5 slots not ilvl for the head+body refresh combo. Better to go get a refresh hairpin and idle in Theophany+1 giving you a total of 5 Refresh and 1 item is ilvl at least as opposed to none. Idle refresh is seriously extremely important you should also get a Bolelabunga, Fucho-no-Obi, and Moonshade earring. This will give you 7 constant refresh and 1 more when low mp.