public static void Main()
var start = DateTime.Today.AddHours(8).AddMinutes(50);
var end = DateTime.Today.AddHours(18).AddMinutes(35);
Console.WriteLine("Start:" + startTime);
Console.WriteLine("End:" + endTime + "\n");
while (startTime < endTime.AddMinutes(inc))
Console.WriteLine("By looping: " + startTime);
startTime = startTime.AddMinutes(inc);
var timeSpan = endTime - startTime;
var intervals = Math.Ceiling(timeSpan.TotalMinutes / inc);
Console.WriteLine("\nSpan: " + timeSpan + " (" + timeSpan.TotalMinutes + " min), intervals: " + intervals);
startTime = startTime.AddMinutes((intervals - 1) * inc);
Console.WriteLine("By interval calculation: " + startTime);
startTime = startTime.AddMinutes(inc);
Console.WriteLine("By interval calculation: " + startTime);