Unless you have a really fast connection 20 slots will be setting a speedlimit. Let's just as an example say you have 100 KB up then if all are filled you will be giving to 20 different uploads at only 5 KB/sec. If you set that on 10 they would be getting 10 KB/sec. Set it on 5, they get 20 etc. (Off course depending on their max download speed) but if one goes slow, the others will speed up in most cases.

I don't know you're speed, maybe it's more or maybe even less than that, so you do the math.

Regarding your download problem:

Set up can really have a lot to do with transfers being interrupted. Like in my case for some reason I can't get my router to portforward Limewire (not because of lack of trying) At least half of my uploads will get interrupted not because any limit has been reached, but rather because of bad setup from my side and maybe bad setup from the downloaders side. I notice often that people that do not have the chat enabled smiley a lot more often will get failed uploads from me than those who have it. Others may stay connected for my whole uptime without a single problem. My slots are almost always full from about 15 minutes from logging on to network and always close to max speed. If one fails another one starts. That could be a reason for some of your downloads failing, if there is a temporary interruption and then all slots + queue are full. A lot of people share video as well and all slots may then be in use for up to a day at a time if not more.

I think you use the worse case scenario to the max. I can not explain why this happened to you, I am not a programmer. I only say that you can't be sure that's the reason

Sleepless