End flashes disappear too quickly

Steps to Reproduce:

1. Set graphics mode to Fancy or Simple

2. Travel to the End

3. Wait for an End Flash

Observed Results:
The flashes last between ~1-3 seconds, disappearing before you can even spot them most of the time.

Expected Results:
The flashes last between ~5-19 seconds, allowing the player to easily see the source of the sound.

Notes: