Planner-list How to do only one thing at a time ?

Hello fellow planners !

I just started using planner and am trying to plan a simple project that
I will be doing in the next few month.

Dependency between task works great, even if I would like to be able to
tell planner that some task can't be divided  : if "go buy something"
takes 4h and there is only 1h left today after previous task, I won't be
sleeping in my car halfway, I will start it tomorrow... but I manage by
adjusting durations.

The thing that bothers me is when tasks are not dependent but don't
account for the time I spend doing them...
Let me clarify : I do no need to do "task 1" to start "task 2", but that
doesn't mean that I can do both at the same time.
I would expect "as soon as possible" to take that into account but
planner still shows the 2 tasks being done at the same time.

Am I doing something wrong ?

I tried using resources to prevent that :
Since I will be the only one working on this, I created a work resource
called "Me".
But if I assign "Me" as a resource to "task 1" and "task 2"... each one
use 100% of it, and so 200% of "Me" is used at the same time.
Poor "Me" is not capable of that. :)

Is there a way to manage this particular issue ?

Manually setting the date seems messy since it would have to be done
again every time there is a change in the plan.

Artificially linking tasks that have nothing to do with one another have
a very great cost of readability

Thanks for your help