I put a Burglar Alarm on out house about 4 years ago a simple Yale battery operated, 4 D batteries last for about two years , 3 PIR sensors for the front toom to cover the door from the hall and front windows and the French door leading to the Patio.
One contact breaker on the front door one on the back door, close kitchen door and front room door when we go to bed arm the system downstairs never had a problem with it going off for no good reason when either in or out away on holiday etc.
Also fitted a Ring Camera Door Bell with speakers to front door, Ring Camera plus spot light speaker and siren to the back of a house , so I can tell anyone in my garden that should not be there to bugger off.
The above can be monitored on our mobiles never had a problem always on when out , if in the back garden Mobile will tell me when someone is approaching the front door and when they have rung the bell.
Both garden sheds have stand alone battery PIR alarms
Never have had a problem so far , whole lot less than £500