How long is Solana staked for?

As a cryptocurrency enthusiast and investor, I'm often curious about the various staking mechanisms in the industry. Specifically, with regards to Solana, I'm interested in understanding the staking duration. How long is Solana typically staked for? Is it a flexible term that can be chosen by the user, or is it a fixed duration? Furthermore, are there any penalties for early withdrawal of stakes, and what factors influence the decision-making process when deciding on the staking duration? I believe this information is crucial for investors to make informed decisions about their portfolios and ensure optimal returns.