We walk, and our religion is shown (even to the dullest and most insensitive person) in how we walk. Or to put it more accurately, living in this world means choosing, choosing to walk, and the way we choose to walk is infallibly and perfectly expressed in the walk itself. Nothing can disguise it. The walk of an ordinary man and of an enlightened man are as different as that of a snake and a giraffe.
(R H Blyth)
If your internal skills are not evident when you work with other people, you should question whether they exist at all. The absolute necessity of partner work is irrefutable.
Partner work separates those who practice tai chi chuan from those who do not.