Why do some work and some not?
More than the question of working or not, the proper identification of support and resistance should be of greater concern. I have so often seen what IMHO I feel is one basic misinterpretation of support and resistance that would lead to failed or missed trades.
As in the attached, so many people refer to the lows in a downtrend, B, as support, such as S2, and the highs in an uptrend, A, such as R1, as resistance. The moves to S1 and S2 are completely opposite, with that to S2 being a move in the primary direction and that to S1 being a reaction. Therefore, the moves following S1 and S2 can not be expected perform equally. So for those who employ the 'buy at support and sell at resistance' tactic, treating both S1 and S2 as support will, as the OP questioned, be hit and miss. Also, for example, regarding R1 as resistance, rather than just the last high in the primary direction, may cause hesitation to buy before R1 is penetrated, resulting in a missed trade.
Additionally, using the white line as an example, looking for support at a low in the previous trend, S3, will not have a high probability of success as the forces at work at that price level are the opposite.
While the above is just basic TA, I've seen such misinterpretations so often that I thought I'd give my 2 cents, even though few will agree or be interested.