so long as you remain perfectly clear, any divination system works perfectly fine. The ABS training is probably the best system on the planet for cultivating clarity. The I-Ching is also very good.
If you can remain unattached to the outcome and can get some good practice with it, in a a kind of working track record then I think it's helpful. I like to use mine as an information source that contributes to a greater understanding but if I needed a fuller source of info I might use several oracles to arrive at a complete picture.
For example, sometimes if we are pretty biased on getting an answer then we might be unconsciously influencing the pendulum, so it's good to first establish a neutral space a kind of circle of protection and try to take a step back from the expectation of the answer you may be hoping and just seek a clear unbiased answer. I have pendulums that give clearer responses than others in their swinging and spiraling and so sometimes that connection can matter in the clarity of the response.
What is interesting is when I use the I-ching and the pendulum both times I get information along side the pendulum responses that kind of caveat the information for a bigger picture. For example last weekend we were stargazing and Jason asked me to use my pendulum to determine which campsite might be more ideal for viewing the sky. We had two choices. One was closer to the cafe we were at and another was about 90 miles further.
I asked if the skies would be clear Friday night in our first pick of campsite and got a weak no and I also heard that it would be clearing up later. I got a yes that the other further campspot that we could arrive at would be clearer but again also later on so they were about equal. We wound up not gazing that night and just telling stories and hanging. We wound up going to the closer spot. It was cloudy and clear in spot and I think it cleared up way later on as suspected. Also, sometimes life is dynamic and things shift and change and so the outcomes are also subject to shifting.