Well I'm older than the OP and my guidelines (to myself) for gates is ...
1. Never text beforehand
2. I have a couple of keys and the combinations to a dozen gates that are kept locked.
3. I have a handful of customers where I use a small "gate ladder" (6ft long cut down top section with ladder mitts) to reach over and slide the bolt(s) with a cuphook thingy on a pole.)
4. I have a handful of customers where the gate/wall is strong enough for me to use my gate ladder to get over easily - and with their permission.
5. I have one customer who thinks I have a skeleton key to get in his gate whereas a quick flick to the side means I can lift it past his pathetic gate stop and open it.
6. Locked gates, or linked properties with access only when the custy is in are fronts only and backs on request - usually by them asking me first and leaving the gate open.
The one exception to all this is a group of 5 detached houses adding up to about £100 with some gates are locked and where there is a disabled lady whose house and garden is like Fort Knox, where I text one neighbour beforehand and he tells the rest that "the window cleaner" is coming tomorrow.
He arranges access and collects money from those that aren't going to be and pays me in so I don't mind texting first, though often he contacts me just before I am due to get the exact day.