Light intensity decreases by the square of the distance. Place a light 1 foot from a surface. Then move the light to 2 feet from the same surface. The light falling on the surface has decreased to 1/4. (1/2x2). So as you have found, task lighting is more efficient. And yes, repainting your ceiling will make a big difference. The cost of electricity for high ambient overall lighting is high too. So the overall lighting needs to be bright enough for safe navigation and work. If you switch your lighting in banks, you can have light where needed, plus task lighting at your work stations. Unless you are using LEDs for task lighting, I would shut them off when not needed.
2 ea 8' fluorescent tubes are about 150 or more Watts depending on your particular model. So each pair uses 150 Watts x 8 hours divide by 1000 kWh per 8 hour period. 1.2 kWh. Multiply that by 30 days x your electric rate of say $0.20/kWh and you will have the cost per month. $7.20 per month. 4' are about half that. So total it up and see what it is costing you. Adjust days, hours, and your local rate accordingly. Then review what you really need.
Tom
My simple numbers didn't include the ballast, up to about 40 Watts for twin 8'. So get efficient ballasts to decrease your energy costs. Also consider that all adds to your air conditioning load if you have air conditioned work area.