How long should I use the rowing machine to achieve optimal results? Is there an ideal duration that balances efficiency and effectiveness, or does it vary based on personal fitness levels? As I embark on this journey of cardiovascular enhancement and muscle toning, how do factors such as my current physical condition, fitness goals, and workout intensity come into play? Should I incorporate intervals of high intensity followed by recovery, or is a steady-state approach more beneficial for endurance building? Furthermore, what role do variables like frequency, rest periods, and overall workout regimen have in determining the duration of each rowing session? Can overexertion lead to diminishing returns, or is it essential to push my limits in pursuit of progress? How do seasoned athletes differ in their rowing duration compared to beginners, and what guidelines can I consider to ensure I engage in a balanced routine? Are there specific recommendations from experts that might illuminate this query further?