In France white collars usually don't work 35h/week. We usually sign 'day contracts' with almost no time limits. On the plus side it is true we have additional days off, usually around 12/per year and if we don't have enough work we can even work less than 7h/day. I don't know any company that leaves you out of work though. In 2014/2015 I worked on an insane project where the estimated delivery date was far far too optimistic. I worked around 9~10h/day all week long sometimes on the weekend too. If I didn't have a 2 months break because I broke my ankle in the mountains I would have gone nuts. After this experience I told myself 'never again'.

Just to complete the story at some point we were referring to this project as the 'cursed project'. The project manager (who made the original estimates) went 2 months to the hospital with a serious depression at the beginning (he had priors). The surrogate acting project manager was at some point on the verge of psychological breakdown and became a heavy smoker. I (lead dev) broke my foot on my first day of summer vacation. One business analyst was hit by a car (survived but multiple fractures). Another dev had an unexplained swollen feet problem (2 weeks off, probably stress). Another dev, external contractor, was terminated because 'he lost the sparkles in his eyes'. And due to the insade delivery rate, sometimes 2 delivery in production per day, one of the ops got burnt out and eventually resigned.