Which troubleshooting method is considered least effective in pneumatic troubleshooting?

The shotgun method is considered the least effective approach in pneumatic troubleshooting because it involves making random changes or adjustments without a clear plan or understanding of the system's operation. This lack of structured analysis can lead to confusion, wasted time, and potentially more issues, as it does not follow a logical approach to isolating and addressing the specific problem. In contrast, systematic and deductive reasoning methods focus on structured analysis and logical deduction, allowing for targeted troubleshooting based on the system's design and behavior. Trial and error, while less systematic, can still lead to effective results if it occurs within an informed context. However, the shotgun approach does not provide the necessary rigor for effective troubleshooting and may ultimately complicate the process.