I have a very specific skill set so my experience may not apply, but I’ve had the best results going through technical head hunters.

Tempt to perm positions lasting six months to a year, then they decide if they want to hire you.

Yes spam away, it’s not like your credit score is getting dinged each time you send one.

My only caution to this approach is that you want to be sure to research the company before any interview, don’t show up and be like “Well, ya’ll were the only one of the 500 I sent out to reply, what do you do?”