@brandyob
It's slow at first. If you are with 150 MSC's you'll likely find that (maybe) half have any work in your area. Thereafter, maybe 20-30 will have work that fits your style. From there, you'll develop favorites. On a daily basis, I might check the 15 job boards for my current favorites. If I'm not finding enough work, I'll check the other 15 that have had work that fits my preferences.
I have all the MSC's for which I am registered bookmarked in my browser categorized as:
"Reliable" These are MSC's that pretty much always have something available to me that fits my preferences.
"Once in a While": These are MSC's that generally have something available, but may or may not appeal to me.
"Rarely" These are MSC's for which I have shopped, but that either rarely have work in my area or whose work I just don't care to do.
"Never Before" These are MSC's for which I have never shopped either because they don't have work in my area or because I have had no real desire to do what they advertise.
When I find myself surfing job boards, I start with the "reliable" companies and move down. I find I check companies on my "Never Before" list once every few months.
Most MSC's will send email out when they get new clients in your area, so I watch those closely - and if the email piques my interest, I go to the job listings and get more detail. As MSC's gain and lose clients and other shoppers become more and less active in my area, my 15ish favorites does change and I might re-categorize MSC's in my bookmarks.
Also, once you become known as a reliably good shopper to an MSC, you may get emails and phone calls offering jobs and bonuses that do not show up on job boards. For my trip to California last week, over half the shops I did were never advertised.
Hard work builds character and homework is good for your soul.