Horary astrology is accurate, but like all other divination tools, it should only be used by people who know what they are doing. It's easy to see a chart and think all sorts if you're not familiar with it. I would only use it for questions that are pressing in a given moment, need an immediate answer and have gained momentum. I consider them to be short term readings, as with anything, things can change depending on your actions. Horary charts tend to be valid for 3-6 months, after this time you're welcome to ask the same question again. For example, some people use it to ask 'will I ever get married?' ... If you're not engaged, in a relationship or even dating, that's a pointless question to ask and the chart will mostly likely show that. Alternatively, if you ask about whether you will get a job and you haven't even applied for it, the chart is likely to show you that in a number of ways.
I've successfully used it for 'will me and X get into a relationship?' and 'will I get this job?' (After an interview) and it's been successful.
I sometimes do my own charts, but I'm not anywhere near as good as Genuine Guidance (I don't know her personally!)