This is my experience having had the unfortunate job of doing well into 400 garden lights, and some never do's - its a personal position not related to any regulation / BS Standard.
1. I simply dont bury a final cct at 240VAC protected by RCD at the main board.
2. I come out of the DB and distribute multicore SWA to GRP junction box mounted on posts or side of building.
3. I then drop down cores, e.g. 12 core to 7 core to 4 core as i move away from the DB further into the garden, this allows control of zones of garden at the 240V level.
4. I install specific Tridonic outdoor drivers in the same GRP above ground box per zone.
5. I then star out from GRp box to individual lights and make connection in the GRP box using din mounted terminal blocks
6. The lights are CC usually 350mA industry standard lights.
7. Where i have to joint cables i use crimps and 2 layers of adhesive heat shrink sleave or if there are some multiple joints i have used wiska boxes, drilled a small hole in the very top and used bullet swajoint resin, warmed up under the bonnet of the vehicle, lol.
Benefits are:
1. one dodgy light or joint will not take out the RCD and subsequently a good number of lights as the drivers handle the fault and it just affects the zone the driver is connected to.
2, fault finding is easy as you can disconnect individual lights at the GRP Box and get the zone back up and running minus the dodgy light.
3. When the gardeners finally chop though the cable, reduced impact as the driver handles both the short cct and eventual open cct, again just that zone is affected.