I always add chicken (2-3cm diced thigh fillets) to the TM bowl with 6-7 minutes of cooking time remaining. I check a piece at the end of cooking time and it is always cooked to perfection. I do this with risottos, curries, honey mustard chicken etc.
Mince is tricky. Some people like it in the TM and some don't. I use the TM if I am making bolognaise for lasagne or macaroni beef, but otherwise I generally prefer it on the stovetop.
With diced beef I find cooking times really vary with the cuts. I made the gourmet beef casserole (recipe from forum) a fortnight ago and used rump steak. I didn't check it (silly me) and cooked it for way too long. It had all disintegrated and looked terrible. The same dish cooked with blade steak would have been beautiful. Tonight we are having swiss beef (recipe from forum also) with rump steak and I will add the steak in a lot later than suggested.
Hope this helps. Good luck!