quick question on stretching duration

[jmula]

i started stretching 30seconds and resting 15 seconds is that enough rest time or to much resting time?

[Realman]

Instead of resting you could just shaking it so more blood can go back to your unit and you can stretch again.After every strech just shake it to get some blood back to your unit.

[jmula]

so how long would i do a shake for after stretching for 30seconds.