Each Applet you enable on IFTTT has information on how often it runs. You can see often they run by selecting the ⚙︎ icon on the top right of an Applet . You'll see some text near the bottom that states This Applet usually runs within [Time]. This is dynamically generated based on the past several times that Applet has run.
You also have the option to run the Applet manually via the Check now button on this screen.
The frequency in which Applets run is largely dependent on the service(s) you're using. If an Applet isn't running as quickly as you expect it, we encourage you to check with the service owner. Most service owners have tools available to them to help them figure out if their IFTTT integration can run a bit faster.