i don't use 學行車 and my girl started walking with hands free at 10m. from my observation, if you use 學行車, they cannot learn how to balance and master their muscle in walking. even if many parents like to carry them by underarm and teach them to walk, they cannot learn fast or turn out walking on the toes. all you have to do is to let them hold on furniture to walk. they must learn by themselves how to use the muscle, how to balance the body and how to fall on the ground. just give them a safe environment.
they have different progress and don't push them. i would worry if my girl walks on the toes (which can't be changed easily even when they grow up to adult and have great impact on backbone) rather than not crawling. crawling is not a must.