Depends on the context. If the audience may suspect that something is concealed then show them to be empty- but often a simple open hand gesture should suffice if that is the case.
However, there are other times when overtly mentioning a method which is CERTAINLY going to be assumed, can be the best thing. In Out of this world I make it crystal clear that I am not switching the deck, using slight of hand to arrange them or anything of that kind because that is what people expect magicians to do. When you are confident something will be suspected then that needs adressing and it is justified to draw attention to it, even if it means finding a way to be able to do that which can get around that. Say for example if you were doing a banknote reading trick (I don't so I am not sure how it is received, but lets imagine for the purposes of this example that the natural assumption from the average lay person was that you were swapping the bill somehow- which you may well be doing) then you could explicitly draw attention to the fact that the bill is not being switched- have it placed in your hand ver cleanly and show that you are not switching it, 'read' the serial number and have it recorded, then thank your audience. Of course they want it verified- and by now you have had all the misdirection you want to switch the bill. (Please remove if this is exposure)
It also depends on your character. Is he someone that is meticulous and frantic about obviating trickery and proving fairness in which case ten seconds to show hands are empty, whilst probably being superflous, is consistent with the character.
Is your character relaxed, calm and nonchalant- in which case ten seconds seems suspicious '

What is he up to?', which is counterproductive.
Character is a worthwhile thing to consider- and if I might make a small point, do not make him too different from the 'real' you. 80% of my audience already know me, albeit somewhat vaugley perhaps, but they will know that I am not a mysterious Deity- but a hyperactive, outspoken know it all/ Inredibly cool Jedi warrior

- so my character therefore is a savantistic sage, which allows me to bring is a certain artificial mystique without conjealing with my genuine character. So use your ideosyncrasies to your advantage and bring them into your character so the contrast is not overbearing.