Funding is exchanged only at the settlement stamp, so a position opened and closed between stamps pays and receives nothing regardless of what the rate was. Some traders deliberately trade around the timestamps for that reason.
Annualising requires the interval. A 0.01% rate every eight hours is three payments a day, about 0.03% daily and roughly 11% a year. The same 0.01% charged hourly is about 0.24% a day and nearer 130% a year, so quoting a rate without its interval is meaningless.
Venues also apply caps and dampeners, and extreme regimes can push funding to the cap for days. Holding a leveraged position through that is a running cost that can exceed the price move you are waiting for. See funding-rate and basis-crypto.
Related: funding-rate, perpetual-futures, basis-crypto, long-short-ratio