You need to keep your wallet opened 24/7
no, that's not true. you can also gain stakes on just let the wallet run for a few hours per day.
although 24/7 is better, it isn't necessary.
I had Moin in my wallet, and while he was offline i did not get anything from staking
Now my wallet is open 24/7 and i receive 1-4 times per day and everytime got same amount. as far as I understood you get staking rewards only from opened wallet time. more time online = more Moin from staking. correct me if I'm wrong