Training to Failure
Strength training to failure is an advanced technique used to thoroughly fatigue the muscles being worked.
New to training especially with weights this is not recommended!
Ideally a few years of consistent training is required to adopt this technique.
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The Advantages & Disadvantages of Strength Training to Failure
#1
The Advantages
♦ Boost muscle hypertrophy
♦ Favors the metabolic process
♦ Use only 80% max capacity
♦ Improves muscle strength quickly
♦ Gain muscle mass fast
#2
The Disadvantages
♦ There can be a risk of injury
♦ Can compromise technique
♦ Too often increases cortisol levels
avoiding the negatives
The link below has good information on for and against for strength training to failure.
Also note below that Circuit Bootcamps, Strength Training and Cardio HIIT are great ways to break up the occasional working to failure.

Circuit Bootcamp
A type of group physical training program that may be conducted by gyms, personal trainers or other organizations.
These programs are designed to build strength and fitness through a variety of types of exercise.

Strength Training
Involves the performance of physical exercises which are designed to improve strength and endurance.

Cardio and HIIT
High Intensity Interval Training is a form of interval training, a cardiovascular exercise.
Alternating short periods of intense anaerobic exercise with less intense recovery periods, until too exhausted to continue.
Tarining to Failure
In conclusion, this type of training may be very beneficial if done infrequently and correctly.
However, as noted above there are chances of injury and possible unwanted hormonal changes.
It would be best to train to failure one major muscle group during the week.
Doing one body part per day will allow safely without injury and I gained great muscle and strength.