It relies on your bandwidth and peers connected ...
If the torrent has already enough seeders, your chances of co-seeding is low ...
For Instance : [bandwidth is divided from 10% of your dl to ul speed]
ex: [dl = download / ul = upload]
download speed = 500 kbps > upload speed = 50 kbps
1 mb dl speed > 100-140 kbps ul speed
10 mb dl speed > 1 mbps ul speed ...
Seedbox has the highest range from ul/dl rates ...
In addition downloading while seeding interfere your speed ...