Yes you leave the cinnamon on. I have retreated some of the stubborn ones after 2 or 3 months but I suspect the good effect is probably used up after a couple of weeks. If you mist the cinnamon lightly for a couple of days it sticks and won't wash off. Looking at the pictures I see some blackening around some of the eyes so if the eyes on the lead pseudobulb are damaged it will take a little longer to get one of the back bulbs eyes to activate. I would coat the whole base and set it on a bed of damp sphagnum in your terrarium and cover terrarium or just in a bag with sphagnum and you don't have to take it out for watering as long as the moss stays damp. I leave plants in bags for months without ever opening them up.
Here is an example of a mini phal (one of 2 plants) that I bought mid December 2010 and both finished blooming late winter early spring. One developed new growth right away and this one did nothing and towards the middle of July I noticed the lead leaf was yellowing indicating a problem in the crown. So on July 14 I sprinkled cinnamon on crown area and base. Today I noticed what I would say is a new plant starting up from base.
Nearly all the plants that I have treated have responded, but I have Cattleya Caudebec 'Carmela' HCC/AOS that I got from Cloud's Orchids that has not put on any new growth since I got it in June of 2009, although it has put out new roots. Gave it the cinnamon treatment 6 to 8 months ago and still nothing. So it doesn't always work, but then again no cure is sure.
The one good thing about cinnamon (no 2 good things) is it won't hurt the plant and it makes it smell good.