I use the OpenHAB automation software (http://www.openhab.org/) and the OpenSprinkler plugin that was created for it and don’t actually schedule anything in OpenSprinkler at all and let my master home automation controller handle everything. I also have been doing maintenance coding for the plugin.
While I personally can’t think of a reason I would need infinite time limit, individuals that use central controllers for all their home automation might have varying needs that could require it. For example, let’s say some one has an OpenHAB setup where they have a Koubachi (http://www.koubachi.com/) plant sensor and an OpenSprinkler device and a number of scripts to maintain a garden. It is possible in this case for OpenHAB to read in sensor data from the Koubachi and have user scripts that activate a watering system through the OpenSprinkler. Now lets say the the watering system is a slow drip system and it takes a day or so to fully water a plant bed slowly.
In a case like this (and many others where central home automation is used), it would be highly preferred the sprinkler controller act dumb and let the home automation controller handle turning stations on and off without interference.