I haven't trained Honey to ask when she needs to go - although she will ask, if she needs to go and I don't notice her at the door.In that case she will come looking for me -and bark. If I ask her does she need out, she cocks her head and goes to the door.
I did teach her a "toilet" command though when she was a pup, and it still woks now - she is 3.
If I have let her out and I need her back in in a hurry, for example if I am going out, I just say "toilet" and she goes.
It is handy for those times where she wants to spend time snuffling about before she goes at her leisure

If I want to be sure she goes, I say "toilet" and then she can sniff to her hearts content
