When I was a line holder my average block per day was 5.5 hours without working any 4 flight days. I always bid low credit, usually mid 70's credit with 16-18 days off then I'd pick up a couple reserve days on top to credit 85ish. For a typical duty day for a turn just add 2 hours to the block time, show 1 hour prior, almost all turns are 45-50 minutes in the outstation plus 15 minutes for the post flight. I'd usually show at 7-8am and was done by 2:30-3:30. In my base the PM trips are usually a 2-4pm shows and done by 9-11pm. I chose to not the bid the 4 flight days so I could always be home every afternoon with the kids but a typically 7hr block 4 leg day is a 10.5 hour day (1hr preflight + 3 45min turn times + 15). They are nice for some people that live farther from the airport and/or want max days off.
With that said I was somewhat senior in a large base with lots of flying, some bases located in the center of the country don't have many higher time single turns. Each base is almost like a different airline at this company since it can be so different. Some of the junior schedules in my base are closer to high 4's block per day so plan on much shorter/easier days but less days off. Now I'm very junior in the other seat and sit reserve (18 on 12 off), typically called out about 5-10 days a month, some of the smaller bases get away with 2-3 days a month called out. I do occasionally get some silly long days on reserve involving deadheads, much more of them in the summer, plus about 5 overnights a year but my neighbor still thinks I'm a stay at home dad. Hope this helps.