Another useful Jenkins plugin is the Conditional BuildStep plugin (https://wiki.jenkins-ci.org/display/JENKINS/Conditional+BuildStep+Plugin). This plugin lets you skip or include build steps based on some condition. For example, you can build and unit test your source on every commit, but only run Selenium tests every three hours using a periodic build trigger (so your build is being tested even though there are no commits).
Install the Conditional BuildStep plugin in the plugin manager. After installation, you get two new build steps: Conditional step (single) and Conditional steps (multiple):
There are quite a few conditions to choose from. The Build Cause determines how the build was triggered (manual, SCM, or timer...), but you can also specify a day of the week, a time of the day, combine conditions with logical AND and OR clauses, and much more....