Mow regularly! Mow at such a frequency that you never have to remove more than a 3rd off the grass leaf/blade length. Kikuyu blades should be about 4cm in sunny areas and 6cm in shady areas. LM blades should be about 7cm long.
Rather irrigate for a longer period less frequently than a short period more often. The roots will grow where the resources are and if you only soak the top layer of the soil the roots will not grow deeper. You want the roots to be as deep as possible in order to be healthier and be able to survive periods of distress (drought or cold) better. Irrigate in the mornings. If the lawn is damp during hot summer nights then fungus becomes a threat.