Example1.cs

using (progress.Start(4 + items.Count()))
{
    DoWork();
    progress.ReportWork();

    DoHeavyLifting(items);
    progress.ReportWork(items.Count());

    DoMoreWork();
    progress.ReportWork(3);
}

Example2.cs

var actionsWithCosts = new ActionsWithCostsList(progress)
{
    DoWork,
    {() => DoHeavyLifting(items), items.Count()},
    {DoMoreWork, 3},
};

// ...

class ActionsWithCostsList : List<Tuple<Action, int>>
{
    public new void Add(Action action, int cost = 1)
    {
        base.Add(Tuple.Create(action, cost));
    }
}

static class ActionsWithCostsListExtensions
{
    public static void ExecuteWithProgress(this ActionsWithCostsList @this, IProgress progress)
    {
        using (progress.Start(@this.Sum(t => t.Item2)))
        {
            foreach (Tuple<Action, int> step in @this)
            {
                step.Item1();
                progress.ReportWork(step.Item2);
            }
        }
    }
}

Example3.cs

var actionsWithCosts = new ActionsWithCostsList()
{
    () => i++,
    () => Console.WriteLine(i),
};

IProgress.cs

interface IProgress
{
    // Dispose to end
    IDisposable Start(int totalSteps);

    void ReportWork(int amount = 1);
}

IProgress2.cs

interface IProgress
{
    // Dispose to end
    IDisposable Start(int totalSteps);

    void ReportWork(int amount = 1);
    
    IProgress CreateChild(int parentAmount = 1);
}