Light Weight, High Reps? Or Heavy Weight Low Reps?

I use to have the general idea that lifting heavy was a good way to build and develop muscle mass, however with light weights and max sets and reps comes tone and definition as you build on the stretngth of the muscle fibres in your chosen muscle group your trying to develop I.e. Biceps. I found that using a max interval rep method using a mixture of heavy and light weight reps in a longitudinal set does not allow for muscle memory to kick in as your making your body constantly ask questions on how to tackle the various weights. Going heavy adds to mass and low reps gives it the core and concentration as you add more fibres an build upon the ones current in the muscle, whilst making more fibre connections. I'm currently using this as a foundation and find that it's giving me signs of progress.

Normally people that are competing lift heavy to gain mass and have a "cutting period" where they use low weights to define the muscle achieved through mass building. So a combination of the two would work well theoretically. Although, again it depends on your body and type.

I am currently experimenting wit the above hypothesis on Max interval training and going heavy and then light. I have found that alternating the compound lifts such as Squat, Bench, and Deadlift between light high rep and heavy low rep each week has added considerable mass, as well as definition to my overall physique because one week ill hit barbell squats for over 100 reps total but only going as heavy as 315. However, the next week ill load up to at least 405 and do no more than 35 overall reps. The same goes for the other two exercises. As for accessory workouts i keep them the same at a high rep low weight training.