Making sure that your wheelchair cushion is comfortable and supportive is very important, especially when you sit for most hours of the day. Having the correct seating is good for my posture and balance, but I can be thrown out of position by very small alterations to my seat. Often when I have had discomfort it has been related back to the seat and how supported I am feeling. When the gel-pack my cushion leaked recently, I had to have a new one and it changed my height in the chair. This had knock-on effects onto my legs and head position. A change of just 1 or 2 inches meant that I had to put things under my feet to lift them up to stop my legs feeling painful.
The cushion is not the only thing that keeps me comfortable. In conjunction with my lateral support and chest strap, I am held in a relatively stable position that has kept me seated well for a number of years. Sitting all day and wanting to be in a good position has implications for normal activities, and being comfortable is especially necessary. Fortunately, over the years I have worked well with some great seating and wheelchair healthcare professionals to keep me in a good position and they have provided lots of input. This service is definitely an important one for people with wheelchairs, so it really should be seen as an essential part of adult healthcare.
One good thing we have found to prevent discomfort is occasionally giving the gel pack a bit of a beating to push the gel around and spread it back out properly. If I am uncomfortable it does seem to help as the gel tends to settle in one spot after a while. I currently have a JAY J2 cushion on my chair.