There are many advantages of bellows blown pipes. But one of the most important things for playing and is they need to be as airtight as possible. Any leakage of air in any of the main places leads to less efficient playing method. Losing air you having to work harder to play the pipes which then makes it more difficult to be relaxed and comfortable.
You need strong lungs to blow highland pipes so having good bellows is like having strong lungs. Bellows are the key to delivering the maximum amount of air for each bellows sweep.
To check the efficiency of your bellows. Take your set of bellows and lay them flat on a table. Pull the top paddle apart so that bottom one remains flat on the table and the extend the top one as far as it will go. Stick your finger or a cork into the tube that delivers the air to the bag and push the top paddle down until it won’t go down any further.
The amount of movement from fully extended until its tight is the efficiency of the bellows, the greater the movement the, less efficient your bellows are and the less air will be delivered to the bag. Our bellows have almost no movement from being fully extended to being tight delivering the full amount of air with each sweep.
Check that no air, even the smallest amount is not leaking from the stocks, bag, tubes and valves. This will lead to more relaxed and efficient playing.