My take: the slow approach tends to produce better outcomes than the volume one — small thing, but it adds up. My take: most matches go nowhere and that is normal rather than a failure — it is not complicated, it is just easy to skip. Are there any free sites like doublelist that aren't filled with spam?
In my experience, vague profiles get vague responses, or none — it is the single change that made the most difference.
Having tried a few, progress is better measured in conversations than in matches — others here may have had a different experience.