I applied six years ago, got in on the first attempt. Initially, I applied to three schools but then added a fourth at the last second. That's all I was able to afford at the time and with my cumulative GPA being on the weak side (3.2), I figured that the best strategy was to apply selectively to schools where my higher science and last 45 hours GPAs and diverse experiences would be weighed more heavily in admissions formulae.
I wound up being accepted to three of the four schools. One directly, two off of waistlists. The latter two were poor choices financially, though, so I ended up attending the school where I had the direct admittance, as I was able to pay IS rates there. Life ended up taking me down another path after second year, so I'm glad that I made the decision that I did. I still have a stupid amount of debt, most of which is for a degree that I didn't even earn, but at least I'm not in the multiple hundreds of thousands I'd have been in had I chosen to attend an OOS school and found myself in a similar situation.
I generally agree with Battie. I understand that things have only grown more competitive in recent years and I feel like more people are applying, perhaps blindly, to ten or more schools per cycle but I... I don't know if that's the best way to go about it? Especially because I'm still seeing applicants getting rejected for silly things like missing a pre-req or not meeting a published GPA requirement, despite that information being more accessible now. It is ludicrously expensive, not to mention that when you apply to so many schools, if you're decently competitive, you're going to inevitably have to turn down multiple interviews due to time conflicts, though that admittedly might be less of an issue now given that many schools have moved to either not doing interviews or are doing them online.
Still, I think a better approach is to look at your application and really, honestly evaluate its strengths and weaknesses (the WAMC subforum is great for getting an additional perspective on this), then doing lots of research into schools that you may be interested in to see how well your particular strengths line up with what they value in their admissions process, how you stack up with previously admitted classes, and how their seat breakdown looks, then act from there. It's likely not the wisest decision to apply to, say, Texas A&M as an OOS student with a 3.0 cumulative GPA, for example, given the paucity of available OOS seats and the average GPAs of the few people who DO manage to snag those OOS seats.