Blake sensei demonstrated the awareness needed to recognise shidachi's timing, distance and cutting style in order to create a fluid kakarigeiko for your partner. The basic principle was to dismiss a poor cuts from shidachi with a block and cut of your own (e.g. kaeshi do) and allow a good cut to complete.
He made this technique look pretty simple but I found it difficult to perform while we were going full pelt. There's so little time to try and judge your aite, assess the quality of their cut and formulate a response. I realise this only improves with practice and I can see how it helps during keiko, as you develop the ability to read your opponent (without the need to think about it).
On the shidachi side I was pretty poor. I lack the mobility to immediately spring back with hiki waza after taiatari, I must be leaning too far forward after my cut or something. As a result my kakarigeiko attacks appear unwieldy with little control.
On a non-kendo related subject... I was well happy last weekend because Derby beat those forest scumbags 1-0. Get in.