I consider it a failure of the company and interviewers if they need more than a few 1hr sessions to determine candidate suitability.
Most companies have 4 sessions : 1 HR phone, 1 tech phone, 1 tech onsite, 1 HR onsite.
But bigger companies (i.e. bigger salary) increase the 'tech onsite' up to 4. Some companies replace one of the tech phone/onsites with a take-home challenge.
If you want more money, you gotta beat the other 100 people who also want more money. Simple case of demand and supply.