To Caulk or not to caulk?

Just had 10 windows installed and while the windows are great, the installation nightmare was almost too much.
The replacement windows with nailing fin were installed like new construction. They nailed them up and used some type of foil tape over the nailing fin and to the tar paper on the wall. They replaced the shingles (wood in the front and asbestos on the sides and back). They did not caulk around the windows as they told me the siding goes into the J channel (not very deep and in some areas, just barely inside the j-channel) of the window and there is no need for caulking. Did not seem right to me but because these installers were crap, I was out of breath from arguing with them over lots of other things. I figured if caulking *is* needed, I can do it myself.
We have had 2 rain storms and high winds and no air infiltration or water infiltration can be felt or seen. (for now )
So, should I caulk or not? Any help would be appreciated

Thanks

Site

My rule for caulking is that if caulking it makes it look better, then by all means, caulk it. Problem is, many people make such a mess when they caulk that it just looks worse when they caulk it than it did before.

Your installers are correct about the j-channel. It doesn't make much sense to caulk to a j-channel (other than for looks) because air and water are able to just blow into the j-channel, and you don't caulk the inside of j-channels.

If they used foil tape over the nailing fins, they did a better job than 90% of the installers around here. I haven't had much success with membranes sticking to tarpaper, but maybe they've found something better than what I've been using.

I always caulk behind the nailing fin before the window is installed- that's the primary way to stop air infiltration. But caulking the siding is sometimes to the only way to prevent water from getting behind the siding, in certain cases.