How does ALS typically progress?

Linearly. Als is a relentlessly progressive neuromuscular disorder. The progression is steady and is not usually associated with remissions. The median survival is 3 - 5 years from diagnosis, although rare cases of survival 10 even 20 years are reported. Patients usually die of respiratory failure due to loss of diaphragm function.
Sequence. This nasty, incurable disorder may start with flickering muscles over hands and/or thighs. Next may experience muscle weakness, which later is associated with loss of bulk. Even later, swallowing, speaking and breathing can be afflicted. Terminal infections may end the disorder.