> For example she could continuously lower corporate taxes for foreign investment for while not activating Article 50 and simply wait until it really hurts the EU. If the EU doesn't give in the UK continues to wait and makes a lot of money in the process, if it does then the UK also wins.

As the irish figured out, arbitrarily low corporate taxes are just not possible in the EU. This approach would also alienate all partners that she needs to work with later in the process, so that's probably a pretty bad idea. Additionally, it would put her under massive pressure from the brexit fraction that wants migration control yesterday, no matter the costs. Last but not least, the EU could just take the stance that the continued announcements of the legal government to invoke article 50 constitute sufficient grounds to start the proceedings. The UK could certainly fight this, but well, there's sufficient ways for the EU to make the UK sufficiently miserable in turn. All in all, negotiation tactics that alienate the people on the other side are not a good idea if you're an island and the economy right across the channel is bigger than yours.