Travelers are responsible for their own authorized expenses, and reimbursement to employees for other employees' expenses is not guaranteed. If you stay with a friend or relative while on travel, you won't get any lodging reimbursement. Check before you change plans. Keep your work days and your weekends straight. You're expected to get to the TDY location the day or day before the work begins and leave the day the work ends or a day later.
Some people go early or stay late to avoid traveling on weekends.