Several options, each would depend on the level of soiling and type as well as depth.
I have successfully cleaned T & G with my Cimex & brushes, and then run the grout brush along edges, corners, etc; then either vacced; up with a wet 'n dry vac;, small porty; & also even a mop & bucket.
I've also used my CRB many times which also picks up the slurry at the same time..
Beauty of this is that the counter rotating brushes get right down into the grout at a better angle.
Again, (in the bad old days), I've used my Gekko wand or Turbo with either my t/m or porty; to rinse/extract.
This though can be fraught with danger if the grout is old and crumbly or pressure too high.
Just as they say, there are many ways to skin a cat, there are also many ways to clean T & G.
Offering add-on services such as grout re-coloring/replacement also puts extra $$$$ in your pocket.
Speaking of this, I have gone out of T & G work in regards to color/replace due to my knees.
However, I always used a little gadget called a Racatac,
bear with me on this..............
This is a small bit of gear that one kneels on, it has a bike seat for your bum, and a chest support as well. It also comes with 2" or 3" wheels, mine I ordered with 3".
The idea is to get onto it, then propel yourself along the grout line, applying colour or new grout as required.
Since I stopped doing this line of work, and no-one wanted to buy it, it has sat dormant for some time.
A few weeks back, I landed a job in a very large shoe store with massive amounts of chewing gum.
Now my knees and back are nearly seventy years young, so I thought outside of the box once more.
Racatac to the rescue, I was able to zoom around the store on the Racatac, treating all the gum prior to Cimexing the carpet.
Store manager laughed at first, but then saw the result and the fact that I was not getting up and down on my knees all the time.
There is also a small tray where I was able to keep spotter, rags and scraper, plus a screwdriver for really hard stuff.
This saved my bacon.
I don't regret my past, I just regret the times I've wasted with the wrong people.
Take me as I am, or watch me as I go.
I'll retire when I can no longer do what I love, or I no longer love what I can do.
Stop moving, start dying........