With any battery chemistry it's not a fuel tank to empty and refill, each cycle causes some wear to either the plates or the electrolyte. However good quality LiFePo cells have rated cycle life in the 3-4000 so it's not really an issue.
More of an issue (slightly) is that the one thing LiFePo really doesn't like is being held at full charge - you get much longer life shuttling them between 20-80% charge or storing them at around 40%
Ideally if you are not using a big leisure LiFePo for camping during daily drive use it would be useful to try and set things up so it's not brimmed full every day but settles around 80% - I'm not convinced the industry and devices are quite mature enough to so this reliably currently but it's a more common approach now in phones to preserve battery life. It's an area I'd tinker with if I had that setup, but that's cos I'm a geek.
In general I would think a modest shuttling up and down by leaving some things on is either nothing to worry about or slightly beneficial keeping off 100% all the time. If you worry about maximum life then consider shutting your BMS down at around 40% when not using for a while and never run under 20% - but realistically shortening a 4000 cycle pack to 2000 cycles is dropping from a 10 year life to a 5 year life (assuming one a day) and for many that's the length of ownership of the van.
