So what do you do when you just don't have enough time to do the work you need to do? Your product is almost ready to ship. You own one of the key components. You're good at what you do, and you're designing and coding at what you think is an unbelievable rate, but there is a LOT to making this thing work.
Panic sets in way in the background of your mind. You're still working diligently, but you need to take time for things like eating and even sleeping a bit. It's getting interesting, this piecing of your jigsaw puzzle of work together, but will it come together in time?
Next, TAKE ACTIVE BREAKS. The trip to the coffee machine doesn't do it for a break. Your body needs to move or your mind won't stay alert, and you need it SO alert! Walk around the building, jog over to see a friend, do whatever moves your body and clears the mind. Make it short, and get back to work.
Finally, REVIEW WITH SOMEONE SMART. If you aren't moving forward, go over your design in an informal review with someone smart. What happens is that you describe your method of attack, and as you do it, it is YOU who will get clearer in what still needs to be done. The friend may add a bit, but you will find your own ways to finish because you've had to describe it out loud.