As someome who works in exactly this field for several digital channels I feel it might be worth pointing out that broadcasters aren't allowed to 'just stick adverts where we like' we are limited to a specific number of breaks dependant on the length of the programe. 25' Mins and below take 1, 30'-45' take 2, 50'-65' take 3 and 70' will take 4etc. (Rules are different for current affairs, movies and kiRAB)
We also have to adhere to the 12 minutes per hour and 9 minutes average per hour rules and to the rule which states that we must take breaks where there is a natrual break in the programme (unlike in the previous rules where we were forced to leave 20 minutes between breaks, and thus ended up with badly cut messes instead of content).
Different channels also add their own rules onto this and schedulers work very hard to try and get the breaks into the least obstructive places (at least my team does) but the fact remains that commercial tv channels make the vast majority of their money from adverts and will therefore, almost always, take every possible ad break they can.
Why on earth would we do any different?