There are several situations when starting in gear with a manual transmission would be appropriate and beneficial. This may require deleting or installing a manual switch to deactivate your car’s clutch start safety feature (standard equipment on most modern cars) or in the case of a Toyota Tacoma, there is already a “Clutch Start Cancel” button for exactly this purpose.
The first and most obvious scenario when starting in gear would be advantageous is when you need to start on a hill. This will ensure that the vehicle does not roll back at all, which is particularly handy in off road situations or any time rolling back on a hill would be dangerous or damaging. This technique works particularly well in 4WD LOW and equally well in first gear and in reverse. Simply start with the engine off, press the clutch pedal, push the Clutch Start Cancel switch (in Tacoma), select first gear, release the clutch, and turn the key. The vehicle will hop to a start travelling forward, which is particularly nice if there is a risk of damage or danger close behind the vehicle.
This technique also works well for driving over steep obstacles, such as a log across the road. Drivers will commonly stop at the log, then begin slipping the clutch to control the wheel speed and get the vehicle to climb over the log. This is very hard on the clutch, which should be considered a wear item that if overworked, will render the vehicle un-drivable. The clutch is also extremely difficult if not impossible to replace in the wild. The alternative technique is simply of course not to stop, and to release the clutch completely well before the log and drive over it, perhaps using left foot braking to smooth the ride out as you drive over it. A third option brings us back to the point of this post, which means starting the vehicle in gear. Simply stop at the log, turn the engine off, then start the vehicle in first gear as described earlier. This technique will allow you to crawl up and over obstacles without slipping the clutch, which is critical for expeditionary off-roading, especially far from civilization and/or in hostile environments.
The third use for starting in gear is simply moving a down vehicle. If you run out of gas or have some other problem that causes the vehicle not to start, but the battery still has charge and the starter motor works, put it in gear and hold the key in the start position to slowly move the vehicle. This may allow you to move the vehicle out of the road and allow traffic to pass, or onto a trailer to get to service. Move the vehicle a few feet at a time if possible, allowing the starter motor to rest and cool down, which will get the most life out of it.
The last use for starting in gear comes into play when you have a clutch pedal failure, when either the clutch hydraulic system or cable has failed. You can continue to drive the vehicle, but you will need to start it in gear and then shift without the clutch. When executed properly, you can still drive the vehicle indefinitely and at any speed.