Most have a fixed interest rate set per year, as per each coin's individual protocol. This can be anywhere from 1% (peercoin) to 10% (synergy).
Normally, what I do is trade coins and obtain them for free and then stake the profits (after having received a little extra bitcoin first). I figure I can just hold and see where things are. During a large increase in price on any of the coins, I'll take some amount of the staked coins and sell them. Maybe try to buy a bit back lower with some amount of the profits. Rinse. Repeat.
Thanks for the reply, does the interest cover the monthly hosting fees in the short term? or do you have to trade to cover that?
I trade enough to 1) either afford paying for the server on its own or 2) not care if it falls short, as this is all speculative.
To be honest, I only just recently started staking wallets on a remote server, so I cannot say how profitable / unprofitable it is. I think having multiple coins staking, with constant internet access, is worth quite a bit to me, so I can turn my home machine on and off as needed.