I have a PM that is built to run daily at 1pm. I now have a requirement to have

Instead of configuring one timer to run twice, you may have better luck configuring a second timer - leave the first set to 1 pm and set the second timer to 5 pm. I don't believe you can set a single timer recurrence value to an array.

This can be done. But not in 1 PM. My method will require 3 PM.
1. - Which will have actual nodes to execute (without any timer on start event).
2. - A PM with timer on start event scheduled for 1300 hrs (Use PM 1 as subprocess)
3. - PM with timer on start event scheduled for 1700 hrs (Use PM 1 as subprocess)

This way you have your code base at one place and executed multiple times. Any change in business can be achieved by doing changes in PM 1.

Also keep in mind that if you use constants in timers then every time you change the constant you need to republish the model too for the change to be picked up by the model. This is because the timer gets activated at design time after publishing the model creating a snapshot of the current value of the constant.

Thanks Eduardo - that is good to know. To clarify, is this for all timers or is that limited to start event timers?

Also, Eduardo, are there any other situations where constants do not get updated without a model republish?

Eduardo, thanks for that information. I didn't realize that.

For now I added a second timer. If the users request a third instance, I'll use Aayush's approach. Thanks for the input!