The idea of having a reservoir of water in situ in my garden pots really appealed to me so I didn't have to worry if I missed a day or two of watering. However, these spikes are not good as a "holiday" watering system as the water just drains out of them straight away - even when I totally soaked a pot through so that, in theory, there was no demand by the plant for water at that moment. I adjusted the outlet hole to the smallest it could go too, but to no avail.
What they are good for is applying water directly to the root system of your potted plants, good for avoiding messes and splashes, good for people who can't carry heavy watering cans as it will fit even the smallest standard pop or water bottle (500ml is a good size both for weight and a smallish pot) and is a good way to apply diluted, liquid feed well into the root system.
So I am happy to use them as a mess free, direct watering system, but I would not recommend as a "holiday" watering system. If others have found the same problem with these spikes, maybe the item description should be changed to reflect this?
I have since found and tried a watering system which uses terracotta cones pushed into the soil and they do seem to work as an "on demand"/"holiday" watering system. Maybe Lakeland's testers could have a look at these as a viable slow, watering system?