In some cases it can work depending on the gear involved, the type of stand used, or other factors. I used to place a VPI brick on top of my Spendor 1/2e speakers and they helped stabilize the speaker/stand interface. However, I find that I don't need to use any weight on my Audio Kinesis Stormbringer speakers.
I also used the bricks on my amp to some good effect, but it was a marginal difference compared with the speakers. Only way to know for sure is to try it out. Of course your selection of weight materials will also have an effect. Lead sacks seem to work well. Fine sand placed in plastic zip lock backs also are a good starting point and cheap to use for a test. Good luck and let us know what you find out.
I also used the bricks on my amp to some good effect, but it was a marginal difference compared with the speakers. Only way to know for sure is to try it out. Of course your selection of weight materials will also have an effect. Lead sacks seem to work well. Fine sand placed in plastic zip lock backs also are a good starting point and cheap to use for a test. Good luck and let us know what you find out.