port security

i have a question related to iptables,
which one is better, blocking the ports one by one, or using one command to block them all ?

like from what ive read usually when configuring a firewall everything should be dropped and then allowing the ports needed.

so does that do the job
or its better to block them one by one ?

basically you have all the freedom to explore, i'd advise you to use drop all and allow the needed.