Depends on what you are painting. Lawn Chair, fence rail, household or garage items, that's the type of stuff where it is useful. Automotive refinishing.....no. One issue is the delivery system, meaning the nozzle. Inconsistent at best. The other big issue is what is inside the can. Low grade material. Almost everything we use now is 2 component. The only place where I have ever used an aerosol was in collision repair when in the paint booth using a "high grade" aerosol etch primer to cover very small sand throughs, before sealing. And that was because I had no other choice and the car had to be painted then.
This forum is about quality. It's about doing quality, long lasting work. To do so you need to use high quality products. Aerosols are not that. Best advice I can give is to not use them. Forget they exist.
All primers are not the same. Some are for corrosion protection and adhesion. Some are for build (fill).
Here are some links for you to read. Should help with the learning curve.
I may have taken some liberties with the original but this is from the old forum: Barry Kives - 14 January 2006 1. Never use a rust converter of any kind. No matter what it is. 2. Never clean metal or paint with lacquer thinner. 3. Never use a metal prep unless you are fully aware of how...
www.spiuserforum.com
SPI Technical Manual. (Read it and it will help you learn about the different products and their applications
How to adjust your gun
General Paint Gun Adjusting Guidelines
www.southernpolyurethanes.com
Perfect Paint Job
The perfect paint job
www.southernpolyurethanes.com
Read topics here on the Forum. Tons of good info here. No BS or false info. Search some of the various member's posts. "Barry" "Jim C" "Shine" "TexasKing" "Crashtech" "MP&C" and me "Chris Hamilton". (sorry to anyone I left out....doing this off the top of my head

" You'll find a ton of real world info on every facet of body and refinishing . All of those I named are Pro's and know what works and what doesn't. Everything you need to know to do a nice job is here on the forum. Just take some time read around and ask questions if you have them.