Moved things were different 20 years ago, in terms of how much money we could apportion for offender need, but probation officers have always had to do some of their studying on the job, in practice placements, post-graduate criminological research and for particular projects, all for the benefit of the service in terms of advancing effective work with offenders. What you wouldn't see in the office was POs studying at home, out of hours, and writing their reports so they could concentrate without office interruptions. It was common practice to do home visits after five, when offenders were coming in from work (lots of offenders have jobs). The unions (NAPO and Unison) encouraged staff to work their hours to the clock in those days, as they were campaigning strongly for more jobs, as probation officers don't get paid overtime on the principle that more people could have employment.
You always get the odd slacker, or office with a particular culture, but in general POs are ridiculously hard-working. Before I retired, most of us did very long hours because of staff cuts, which have been savagely reduced even more, to levels that are judged unsafe.