A 20 minute development time is not unusual, but you can increase the strength to reduce the time it takes. However, a lot of the fun stuff (i.e. colours) happens with the weaker dilutions. As mooseontheloose says, increasing the temperature will also reduce the time it takes for an image to appear - I sit my dish on a tray warmer and run at around 32C and development times are usually around 8-15 minutes depending on dilution and formula.
The next thing to try is toning with KRST, gold, sepia, or even copper - Some of the combinations will blow your mind