Kroll,
Yes that is what I found has worked the best for me and others that I mentioned.
Metal prep, primer, filler, primer, finish coat.
The filler adheres to the primer just like the finish coat, putting filler on bare
steel seems like finish coat on bare steel. And yes every time I removed old filler
it always was rusted or loose. If it was over primer and primed over it was
always intact and NEVER loose or rusted. You had to grind to remove it, not pop
it off like when it was on bare steel.
I have not used a solvent based glazing putty for over 20yrs. I use a ultra thin
2part glazing filler that is for a lack of words, ultra thin fast set bondo.
You never get edge bleed 2 weeks after you finish like with solvent based glazing
putty.
Hope this might help.
Take care,
Rick