The Indesit dryers are tumble dryers and one of the main reasons that causes drying time to increase is overloading. Overloading may prolong drying time. It can also cause uneven drying because the clothes cannot tumble properly. Also the sensor will take longer to detect the cloths are dry and this will result in a longer drying time.
One other factor in increased drying time is the lint filter. Failure to clean the lint filter can also result in longer drying times. Clean the lint filter after EVERY LOAD so the dryer's air flow is not obstructed in any way.