When doing a primer coat do I need to get everything or can I pretty much fly through it leaving it kinda blochy?
I find that primer dries so fast that you have to do the job quickly, but it's worth it in the long run to get it somewhat even: any time saved by doing a poor job of priming will be more than made up for trying to get the finish coats looking good.
The primer coat doesn't have to be perfect, but it should cover the surface (no bare spots) and it shouldn't be so blotchy that you get drips or visible unevenness.
You need to prime the surface thoroughly. The purpose of the primer is so give the surface uniform absorbtion properties. I'll need an extreme example to illustrate that.
Recently I tried to paint the wall already covered with glue liming - the cheapest water-dispersion paint possible. The old paint had good adhesion to the wall and looked solid, but when I started to paint I just couldn't shade the new paint - when the new paint contacted the old one the latter absorbed all the water immediately and the new paint got dry before I could do anything.
This is how I found that priming is a good thing. However that was not all. I discovered than when the first layer of primer is applied it looks uniform at first. However when it dries up and I apply the second layer I see dark spots - those are areas where I underapplied the primer during the fist pass and now those areas still absorb water and thus become dark. The third layer of primer doesn't leave dark spots anymore - all the surface is thoroughly primed and the new paint applies allright.
Once I tried to paint over the first layer of primer - it turned out well except those underprimed spots where paint would still dry up very quickly and wouldn't be shaded well.
The bottom line is: prime with at least two layers until the primer doesn't leave dark spots on the surface.
If priming / sealing bare wood substrates, never apply more than two coats, one coat is best. The substrate is now sealed with the first coat so a second coat will have nothing to hold to. Yes, I know the rule of thumb is a maximum of two coasts of prime / sealer / bond coat or whatever but no more than two coats.
If you decide you need two coats of primer then lightly abrade your first prime coat with 220 grit and simply let the paper do the work, do not press and gouge, etc., then apply your second prime coat and then your final top-coat(s)
Thoroughly remove all existing sanding dust prior to top-coating.
When applying your primer, you will want to make sure it is at least a thin coat over all areas to be eventually painted; if not your paint job will look tacky and blotched. Also make sure you evenly coat your space, not doing so will cause a difference in your paint color (meaning some areas will by lighter/darker making your space looking as if your 10 yr old nephew was the painter) lol But seriously the primer need not be perfectly applied in straight lines its the paint whch will require your patience and time. Turn on some usic loosen up and have fun with it, won't seem like work and removes a level of sress! Happy painting....;)