Fusion Time-Locks are not the same as Time-locks on many other chains or smart contracts. The term is most commonly used to denote locking access to an asset for a specific period of time. Fusion Time-Locks are completely different from this and the term is therefore confusing as it has an entirely different use-case often misunderstood by receivers of time locked FSN tokens. To avoid confusion it's better to call TL FSN and TL tokens slices rather than locks, since it better describes what they are, how they're derived and how they can be used.
When a token is sliced it's split up in two parts, one part can be described a slice limited in time (here TL can denote Time-Lent) and the other part can be described as an infinity end (here TL can denote Time Limited as its usefulness is limited for a time, but it's not in fact locked). Both slices can, if desired, be sliced even further into another two slices of time. Thus there is no limit as to how small fractions of time FSN or tokens are split up. You can also combine together smaller slices of FSN to form bigger slices as long as the dates match up.
Though there are no limits in how small fractions of time you can slice FSN there are limits to how useful it is to split them up too much.
The primary use case of TL FSN is to purchase tickets for Fusion's ticketed Proof of Stake consensus. To purchase such tickets, the TL must be larger than 30 days into the future and thus time slices of FSN that span less than 30 days into the future can't be used for this purpose, unless they can be merged with other slices to make them big enough of course. In most cases, however, it means that only time slices that are bigger than 30 days will be able to generate any FSN through staking. Ideally you want a slice to be quite a bit bigger (perhaps 4 months), so that you can derive at least 75% of the value from it (3 months of staking, and one month of inability to purchase tickets).
What many receivers of TL FSN think will happen is that once they've waited the specified time, they'll be awarded with full FSN. This is a very dangerous belief because, while all that waiting is done the chance to extract interest from the TL FSN has been spoiled.
The use case of Time Slices, is however, not solely limited to FSN. Once it becomes possible to use TL for FRC20s the functionality could be applied to all of crypto and perhaps it will be possible to extract value from other crypto assets as long as it's possible to extract interest from those tokens. This could be staked tokens, but it could also be liquidity tokens who receive some reward, or security tokens who recieve some form of dividend.
Looking beyond pure crypto assets, the usefulness can be even greater. Imagine real world items such as houses or cars controlled by cryptographic keys tied to an NFT, where time slices can be used to rent these out. The lender could receive the benefits of full ownership, except that it'd only be for a specified time after which the true owner gets it back automatically.
The functionality of TL on a protocol level is in my opinion what truly makes Fusion unique from other networks as it is tough to imagine another chain copying this on the protocol level. The reason why I think this is unlikely is not because it'd be difficult to do, but because it's rather messy and might jeopardize many things that other chains may not be ready to jeopardize. Either way, Fusion will always be the first to have this and will have had it long before anyone else considered it a good idea.
If you are here because you have received some 2-4 month TL FSN and you're not sure what to do with it, the best idea is for you to send it to a staking pool. Currently Nodenetworks is recommended as a pool that'll bring you a hassle free experience and good customer service.
What you absolutely should NOT do, is try to send TL FSN to an exchange, because it may result in them being lost to you forever.