Hi Kyle,

If time-crunched, there is an advantage to a higher % of HIIT but no real additional benefit of a higher % of threshold or sweetspot. It is similar to the question “should a beginner do more threshold”….the evidence suggests not. More HIIT can be an entirely different training focus eg TIZ 40:10:50 (seiler z1, z2 z3) is HIT/HIIT training…..but usually this is rather extreme for most people and risks burnout. Most athletes can adjust their TIZ more subtly depending on the time available *within a polarized plan*. For example, let’s say you have 8hrs of training time per week, you might go for a sessional plan of 72:8:20 (converts to TIZ of 85:5:10) but if you only had 4 hours I would suggest 65:12:23 (converts to TIZ of 82:8:10). Footnote: “sessions” is how many training sessions are allocated to that intensity and “tiz” is how many hours of training are allocated to that intensity. If you wish, send me your desired training hours per week and days per week to coaching@fastfitness.tips and i will send you an optimal sessional plan. happy training ! alex