Do SS Transaction Logs Have To Be Backed Up For Recovery To POF?

Coming from a (mostly) Oracle shop, I am unclear how SS transaction logs
work as far as up to point of failure recovery goes.

I have the few MSSQL databases I look after in full recovery mode, and I
set up maintenance plans to back these up online on a daily basis. In
the research I did it was recommended backing up the transaction logs as
well on a frequent basis to ensure recovery to POF or point in time.

I had assumed that they work like Oracles archive logs, in that once
they are full they are archived to disk in case they are needed, to
duplex destinations if need be. Does SS do this, or do I need to be
backing up transaction logs on an hourly (or shorter) basis? In looking
at enterprise manager I see that it does not look like the transaction
logs are archived anywhere, but overwritten once filled up, similar to
Oracle noarchivelog mode, in that if you lose your online redo logs or
anyone of them has recycled since your last backup, then you can only
recover to the last good backup.

Is this a correct assumption? Should I be backing up transaction logs
hourly to make sure I can have PIT or POF recovery?

thanks

TG