What I've been told from numerous people-in-the-know is that going on the job market selectively makes no sense; if you're ready to apply to some jobs, then you should be ready to put your shoulder to the wheel and go forward full-bore with the applications. I pushed back on this sentiment at first. I wanted to leave open the possibility of applying selectively (just in case the perfect job satisfying all my academic and geographic desires came about), but I've come around to share it for the following (non-exhaustive) reasons:
1) Being ready for the market is all-or-nothing: you either have your dissertation done (or close to done) so your letter-writers can say that you'll have your Ph.D by the time of appointment, you either have publications or don't, you either have a job market portfolio prepared or not, et cetera, et cetera.I'm not entirely sold on whether or not these reasons compellingly speak against a selective job search (or make sense, especially the third reason). But, if these don't do it for you, I'm sure people can build upon them (and attack them accordingly) as they see fit in the comments. So, have at it!
2) A selective job search, if conducted because you're not completely ready to apply to all kindsa jobs for the above reasons, more than likely won't be successful. That time you will have spent applying to jobs will be wasted. It's oh-so-precious time you could have spent finishing the dissertation, getting published, or getting a jump on the job market portfolio.
3) There's an off-chance that a job search, if conducted before your eggs have hatched, may hurt any future chance you have at getting that job. If that job is so dreamy as to draw your application and it isn't up-to-snuff, then if it isn't filled, there's no reason for them to take your application seriously the next year. First impressions matter (and perhaps there's a chance of those first impressions hurting your philosophical reputation elsewhere?).