I can’t think of any feature in Project that forces each task to start on a new day as this goes against one of Project’s primary objectives which is to make the best use of resources and create the shortest possible schedule.
However, if we think outside the box a bit I can think of something to try. No guarantees….
It doesn’t sound like the amount of work entered in the schedule for each activity is that important for scheduling purposes. Using your 8 hour per day basic calendar, can you simply create every activity as an 8 hour task? This would allow MS Project to follow it’s natural algorithms and result in each task scheduled on a separate day. And if there are multiple teams, each could have it’s own service call task on the same day because the assigned resources differ. You could even schedule 4 hour tasks if you know that the team can do one task in the morning and one in the afternoon. The down side is that planned work wouldn’t be that accurate.
Again, no guarantee, but it may be worth playing with and it may spark other ideas.