I found a recipe (Wonderful Salsa at Food.com) that called for it to be processed for 10 minutes. I'm seeing now that other salsa recipes call for 15 or more minutes. Is this true for all salsas, or is the 10-minute processing time based on the recipe and thus all right?
Time is not a reliable indicator for for botulism safety. The critical factor is heat penetration which depends on container volume and shape as well as time and temperature.
I worked on the autoclaves in a salmon cannery. Pressure cooker times varied from 20 minutes to 60 minutes depending on the can volume. These times were determined by actual measurements of heat penetration into test cans.
"Looking carefully for signs of spoilage" is foolish. The toxin from 6 individual botulinum bacillus is enough to kill you. Follow authoritative recommendations.