Probably 60% of the time, we have to open drives here.
Similar range here... primary reason is because end users and [no offense intended] inexperienced computer repair techs push the drives too hard, leading to severe mechanical failures and subsequently media damage. Every day, there is at least one unfortunate end user whose files went to dust.
More specifically, the problem with pushing the drives too hard is two fold:
1) Creates more damage (bad sectors, firmware & mechanical damage of various degrees), thus increases recovery complexity, and
2) It increases the price/quote
These circumstances make it unaffordable for the end user to proceed with the service. No-win for the end-user, computer repair shop or the data recovery specialist. Everybody involved wastes time and resources, therefore no gain. Sad.
Should, either, the end-user or computer repair shop wisely decide to forward the service to the specialist, then the higher chances the end user will get their files recovered, the computer shop will get their referral payment and the data recovery specialist makes some money - everybody wins/happy.
Less individual greed, more transparency and honesty make a huge difference.