Since at least the late 1980s pretty much all call centre operations produce reports (on demand, and at regular intervals such as daily, weekly etc) to show exactly how long on average calls are on hold initially, how long they last once answered, how long on hold over the complete call time, how many calls drop out on hold before being answered (initial attrition rate) etc. Then there's the greater detail aka the statistics - a table showing the break down of # calls taking A to B seconds on hold, B to C etc, the same for time being dealt with. Pretty much everything is there for management to see.
Lenghty periods on hold are a senior/top management decision if they last for more than a few weeks. Long ago (pre-internet let alone smart phones), one Australian big 4 bank CEO was talking with potential major Superannuation customers (industry funds) at his bank's function for them. When one of them asked why it took 'so long to speak with someone'? The CEO didn't do a brush-off routine, but asked roughly how long was it, what day of the week & time roughly. 'Nearly a minute, last Friday lunchtime'. His response was accurate & honest (who'd have thought!).
'Friday from 11.30 to 2.30 is the busiest time each week as people often check to see their pay has arrived or they've got enough money for their planned weekend, we aim for no more than a 75 second delay in answering by a person, if you choose IVR then there should be virtually no delay. For nearly all the rest of the week then the delay to speak with someone should be less than 30 seconds'.
Back then speaking with someone was the second option on the initial menu, now it does not come up until the next level down menus and only as the very last item mentioned. Typically more than a minute before you get there and then go on hold & wait to speak with a person. However pushing the appropriate number, often '0' works at any level for most, but not all systems. More 'enhanced systems' deliberately will not recognise a single '0' to stop people beating the system aka speaking with a person - such as where FF numbers are entered - a single '0' can be recognised as wanting to speak to a person but is deliberately responded to with a message like 'Account number not recognised'.
Customers are such a nuisance.