You might be curious why I encourage you to join every new safelist mailer. Probably you belong to several safelist and feel like that is enough.
The real truth is that I belong to more than 100 different safelists and regularly use about 50 of them. In addition, I join most new sites that have any potential to test them out. I had to try many, many traffic programs in order to find the ones that work best for me. You need to do the same.
I always join new programs as well because new programs convert better. When a site is new, there are lots of fresh, new members and the open and click rates are higher than old programs.
If you want more success, you should try dozens of programs and join most new popular traffic programs. Keep track of which ones are generating good traffic and signups. By doing this, you can weed out the ones that are not performing and stop using them. You will never know which ones are the best if you don't join them and try it out.