I bet those 30-odd, 60-odd, or 100-odd flame-throwers did not attack alone, before their attack, there must be a heavy artillery firing, and they must be covered by machine gun and grenades from other stormtroops, and as soon as they "broke" a hole on the enemy defense line, the regular German troops must immediately followed, otherwise You know machine guns and rifles had a much farther effective range than the flame-thrower.I can not imagine a picture in which those 30-odd, 60-odd, or 100-odd flame-throwers calmly walked toward enemy line and enemy either ran away or throw down weapons before them, that would be a movie. Would be possible that those large number of prisoners were not captured by those pioneers alone?
There were many different FW attack schemes developed, but they could be broken into two groups; one, the massive attack, perhaps with a heavy barrage, long or short (remember the two minute barrage at Malancourt), then perhaps an initial flame attack by heavy, longer-range fixed FW, perhaps firing diagonally across the front with flame oil blended to provide dense black smoke, to provide cover for attacking light FW and storm infantry, and then a large number of light FW teams storming the positions, along with many grenadiers. (Almost half of the troops of a flame company were specially-trained dedicated grenadiers, armed in part with special storm stick grenades. - No, that is too many, but there were many grenadiers.)
Or, the second main class was one of a wide range of usually smaller, mostly sneaky tactics, almost all rather counter-intuitive. Very often these smaller attacks might be performed by flame troopers alone; they were reliable, they all knew the several tactics, and they were heavily armed with a variety of crew-served weapons, and generally carried few or no rifles, perhaps some NCOs carried a slung carbine.
Of course, in a larger attack (or in any attack), there certainly were other infantry about, taking part or not taking part in the actual assault. Generally, on a WW I battlefield, if your position was overrun by the enemy's storm troopers, and you were still alive, probably the only good chance you had of surviving the day was to throw your weapon away, put up your arms, and run toward the enemy lines.
Again, large amount of soldiers gave up must involve the moral issue, flame-throwers though powerful, could not be effectively used without suppress enemy fire first, and even after broke into enemy line, without immediate support from own troops, I failed to see why those breach could not be immediately seal by determine count-attack since I doubt usefulness of flame-throwers in the trench and how they re-charge these things?.
For example in the siege of the Petersburg in American Civil War, Union army blew apart Confederate defense line by a powerful mine, union troops poured into the breach, but Confederate line still held, there was no panic, both flank held, and the survivors of the mine attack did not run away or surrender, they count-attack, it won time for the arrive of the confederate infantry and artillery reserve, and Union attack was repulsed with heavy losses. In the most of time in the military history, moral is not everything, but moral matters a lot.
Again, many variations, but a smaller attack would generally just take the enemy front position. Larger attacks would invove other formations and might develop into a real break-through. There were many variations, but the typical flame company might deploy 32 FW (the company would have two or three different types of FW in their trucks, mostly light, and could decide on the spot the mix of devices to employ, due to the tactical situation), six light MGs, that could even be fired from the hip at the walk, and two especially light (20 kg) 76 mm Minenwerfer that could be carried on the back of one man. Many of the men were trained grenadiers. (My "almost half" above is too high.) The light MGs in my father's company were captured French LMGs, so that ammunitions and even loaded magazines might be found in the captured trenches. The men were cross-trained on enemy weapons, including dropped rifles, and grenades that would be found in the hastily evacuated position. So this flame company could put up quite a fight holding a captured trench until infantry came in and took it over. The FW was generally a really poor defensive weapon by itself, and it was possible but usually impractical to refuel the device in a captured enemy trench. But each fire team usually carried two flame oil/propellant tank assemblies for each flame lance; the typical Trupp of about ten men might have two lances but four fuel back-packs. Each device could be fired repeatedly until out of fuel and the operators carried several igniters, which could be quickly changed.
But, do not think that the FW operators simply lined up in a row and walked across the no-man's-land until they got in range. Remember, they averaged one man killed or missing per attack, and in most attacks they did not lose a single man. They could not achieve this record if they did dumb, suicidal things on the battle-field. And I will make a strong argument that the flame regiment's casualty roll was uniqley accurate and complete, for the whole war and all combatants.