I have used them in the past long ago..
They are a hit or miss really, some last for a very long time (6month+) others last for a few days.
While most of them typically do provide "free replacement" over x month period (sometimes lifetime), it is still a hassle (got worse over the years) due to spotify's algo on being in multiple different family accounts within the same year period.
If you are using it for personal use due to shortage of money, or just saving expenses, sure, get a dummy email (use an alias system protonpass/ducks/icloud etc), and import your songs in it, (something like SpotMyBackup) since every time it gets downgraded, your gonna need a new acc & import them back in. This hurts your weekly release/recommends though which kinda sucks.