The recommended max it can be run at is 12posts/day and 5 links/post, per site (self-hosted or otherwise.) And per hosting account, they recommend max 5 installs.
No matter how many sites you use, those 5 links that go out with each post will be for the same profile link...so no matter how many sites you may be posting to, it will be the same links being posted for each install. But with up to 5 installs, you can vary this somewhat.
Anyway, let's say you have 5 installs running to the max, and you've got them setup so that each install is posting 5 unique profile links each post. That's 25 unique profile links each post.
25 profile links, multiplied by 12 posts per day = 300
So about 9000 links a month (roughly), per hosting account.
That's if you're running it to the max, but even then you might have problems with web 2.0 sites. I've had a few web 2.0 properties taken down...maybe because of excessive posting, and posting nothing unique (who knows), so SHWP would be good if you have the option of spreading around where they are actually hosted. (c-class ip's)
BLE, on it's own, isn't enough. But it can only help along side other methods of indexing profile links so I use it anyway. Setup is time consuming but after that it's close to automatic.
When I first got BLE, I ran a quick test with a small batch of profile links and over 2 months only about 35% got indexed, which is pretty crap really.
Overall, I wouldn't say it's the quickest method to indexing profile links. 9000/month is not that many at all...and with questionable success too!