It depends on what type of gambling games we play. If it is luck-based games, changing the strategy won't impact much. However it it is skill-based games, it may bring an impact. It is actually something normal to change the strategy in gambling even if I'm not sure it will have a significant impact for the long run. We know the luck factor will always take the main role in gambling.
Inasmuch as changing strategy and approach might seem like the appropriate thing to do, especially when on is currently experiencing a losing streak, he might feel maybe it's the strategy or approach and thus feel the need to change it. While this may seem like the best move in most cases, it could also turn out to be the worst, because I've seen someone who uses only one strategy to gamble every single day, some days he goes home blessed with loads of profits and sometimes it comes with its own losses, but regardless of the outcome, he still maintains his approach. I don't know if I'll say this is the best thing to do, but I feel everyone has their own unique approach to gambling and it's about sticking to what you think actually works for you.
I think kawetsriyanto is making some good point, not every aspect of gambling requires a gambler to be often strategic, they should know when to rely on luck and when to be very strategic, I think being strategic is mostly with casino and slot games and like the OP said, sometimes you don't need to randomly change different strategies but be patient enough to master a particular strategy till I attracts luck.
The worst is copying someone's strategy that you're yet to master just because you notice they're doing well with it, such might work for the person but won't work for you and you'll begin to wonder why, the difference between you and that person is that he's mastered his strategy and know when and how to apply it but you're depending on his effort to attract luck which might not work for you.