The next trade has an assigned time that your builder cannot change on short notice. Sometimes a trade contractor arrives late because work at another site took longer than expected. Because of that rescheduling, your home may lose its place in line with one of the affected trade contractors. At several points during construction, progress stops until the work up to that point passes required building department inspections. Items noted by inspectors must usually be corrected before work can continue.
Few homes go through construction without an inspector citing something.
Sometimes shipments arrive incomplete or damaged. Work may be progressing quite well even though you don't see much change. If these scheduling delays cause you concern, remember that your builder works with these circumstances every day. All existing homes were subject to the same factors. Quality Many builders have developed formal inspection procedures.