You should endeavor to spend as much time at your house sitting assignment as possible. If you're going to spend many nights away from the property then you've defeated the purpose of house sitting. The house needs to have its usual occupied appearance in order to deter criminals. This means that you need to be there to make sure that junkmail is collected on a daily basis, that pets are walked and fed regularly so that they're not lonely and bored, that lawns and gardens are watered, that the answerphone is cleared regularly and messages are passed on, that utility bills are paid so that services remain connected. Above all, remain contactable while you're in the property so that the home owner can enjoy peace of mind while they're away. A written update on the pets and the property emailed to the home owner on a regular basis can do wonders to reassure absent home owners that all is well.