When I rented a house I mopped them every night with a damp mop. This exercise is what convinced me to never have oak floors. It was a small area so it wasn't so horrible to do, but for a person like me who likes a pretty high standard of cleanliness, oak just didn't work. I now have a dark stain and I am down to once a week damp mopping.

Vinegar, linseed oil and mineral spirits (white spirit) mixed in equal parts to renovate wooden floors or antique wood that is not varnished. I use a pickle jar, adding a plastic cup of each.
The jar lid lets you shake it like a vinaigrette so your mixture can be re-distributed regularly with a cut up T-shirt cloth. It removes dirt using the vinegar and solvent. It soothes the drying effects with the linseed oil. N.b. this does not require refined linseed oil.
Inexpensive concoction that really is worth trying on all non-varnished or poly-ethylene wood.
Careful on stained surfaces. Always try a sample in an unobtrusive place to test before proceeding.

Get a very lightweight, cordless stick vacuum ... I use mine daily to keep the floors spotless.

I have a Hoover Linx .. with an extra battery backup. About $100 .. Walmart/Target.

I hear steam-mops are great for wood floors!

Yes, please be careful applying any water or acidic solutions directly to your wood floors as you could do long-term damage.
Are you using walk off mats in entry ways to remove as much dirt, etc- from shoes as possible before entering your home? It sounds preventing dirt from entering the home may be helpful.

There are so many types & brands of finish on the market today (as well as have been used over the years) it's difficult to suggest a "one size fits all" approach to hardwood flooring maintenance...
However... it's better to be safe than sorry...
NEVER use any more water while damp mopping than will evaporate in 3-4 minutes...
NEVER steam clean, regardless of how many times you see the ads on TV.
NEVER use a product that will leave a residue behind... such as waxes, silicones, oils, etc.
NEVER use (as suggested) anything harsh enough to break down the finish in place.

Dust mopping & using a vacuum with the correct attachment are the best & easiest approach.
Spot cleaning when needed... using mild dish soap (diluted) for example, on water soluble spills such as food/drink, and mineral spirits on oil based spills, is a preferred approach.
The BONA maintenance products are good, because they are produced to maintain the Bona Finishes, and those similar.
Obviously, you don't want to use a product or system that will leave something behind that may inhibit your ability to apply another coat of finish down the line if desired.
A RE-coat is much easier & more economical than needing a complete RE-sand & finish.
Regarding frequency... that's relative to the lifestyle, color, finish style & type, etc..

People who suggest that wood flooring is bad because it shows debris don't seem to understand that just because one doesn't SEE the dirt, doesn't mean it's not there.
To each his/her own I guess.

+1 for using Bona...