This. Cellular triangulation is not tight enough for the google maps to know what street you are actually one.
Navigation needs that resolution to direct you, so GPS is required.
Cell: 10 yard diameter circle (IIRC)
GPS 9 to 13 feet with direction and a center point
Think you have a big typo in your cell accuracy.
Cell is closer to 100-300yard
radius. GPS is sometimes lucky to get within 15 feet (radius of that 10yard diameter you mentioned for cell).
To the OP. Leave all three options checked under Location and Security.
Wireless (cell) uses tower locations to get your approximate location. Under maps you'll see this as a large circle approximating your location. This is useful to get a quick fix and for other reasons mentioned below.
GPS gets a signifgantly more accurate locaton (and required for Nav).
Assisted GPS improves signal lock time.
If GPS is better, why not disable wireless (cell) location? GPS uses more power and if you have an application that constantly looks for location (for instance, a weather app), then all you need is a quick approximation so it knows what city your in to report the local weather. Don't need GPS at all for those operations. GPS will only be used when necessary.
I've seen examples of where the wireless location was disabled and the app tried to lock onto GPS in a building, couldn't get a signal and kept trying. Drained the battery very fast.