When doing CQB training there are two types of entry methods used when entering an urban structure. Depending on who you talk to you will get a lot of different opinions. Some units even use both methods depending on the nature of the entry. Much of this also depends on unit size and equipment you are working with. If the unit is smaller or is a single person the majority method should most definitely be covert entry. But if you have a large team that is well equipped and stealth will be an issue then you are more likely to use dynamic entry.
Dynamic Entry- the method employs speed and surprise to overtake the enemy by use of distraction devices, breaching tools, explosive entry methods, and larger well equipped teams.
Covert Entry- this method employs the use of stealth and cunning to surprise the enemy. Covert entry is used to eliminate risks by using techniques such as cutting the pie or utilizing recon methods with mirrors, video, etc.
I am a personal believer in covert entry because if you do your job correctly then the enemy has little to no idea where you are in the target facility and that makes you a hard target to respond to. When moving through hallways you move with little to no noise and before you enter a room you make sure to recon it. Recon can be something as simple as just using your ears to pick up on any movements, using a mirror to look under doors, or you can use the slice the pie method for checking rooms. But upon entering any small enclosed space it should always be done dynamically after it is reconed. Whichever method is used it must be done with deliberation and planning. Any intel that can be gained about the facility prior to moving on it is extremely useful. Moving on a facility blindly can be very dangerous because of the lack of knowledge about ambush points and dead spaces in rooms.
Whenever a room is cleared the first person through the door must move through the door with extreme speed but slow down whenever they enter the room. After the initial entry is made and the second team member is through then speed becomes less of an issue and identifying targets or potential ambush spots becomes the major priority. You also cannot shoot as effectively when moving at high speed! The second man should literally be brushing by a millisecond behind the entry man. The two man teams main priority is the exterior walls of the room. One man breaks one way and the second man the opposite. If there is a third or fourth man then they will take the middle of the room.
The immediate danger is always to the entry man, so he must be on his game. Each team member must be on his game because when room clearing your life depends on your teammate doing his job with correct timing and precision or it may cost you your life. Any MOUT team should train together for long periods of time so that they intimately know how each man operates in different situations. Communication is the key to success in this business and each team member absolutely must be on the same brain wave. These videos below will give some understanding of how these teams should operate! But these videos are not an endorsement of any particular technique but to just demonstrate these methods.