Half marathon pace is essentially threshold, for a high caliber 3k-5k guy lactate threshold will be somewhere between 10 mile to 13 mile race pace.
My answer to your question would be variety! You won’t lose Vo2Max, or speed, or lactate threshold/tolerance by not doing it for a week, especially if you are hitting other strong stimuli. It also keeps the mind fresh and away from mental burnout longer.
One week you could do something like:
Mon: 12x400m @3k pace W/400m jog (Vo2Max Stimulus)
Wed/Thurs: 3-4 mile tempo, 4x200m @ 800m race pace off of 1:30-2:00 rest (lactate threshold/tolerance)
Saturday: Easy long run w/ 6x100-200m hills with long rest at the end (aerobic/speed)
The next week you can do something like:
Mon: 6x300m @1600 working to 800m pace off of 2:00 rest (speed, anaerobic endurance)
Wed/Thurs: 10x800m @8k-10k pace off of 400m jog or 2:30 rest (high end aerobic/sub Vo2Max work)
Saturday: Quality long run, either steady, progressive, or fartlek, but 7-8/10 effort type day. (Threshold/ Aerobic)
If your athlete is racing 3k/3200m/5000m one week, that can replace their Vo2Max workout, if they race 800/1600m, that can replace the longer speed or anaerobic endurance day for the week. I’d also recommend doing 2-4x150m depending on freshness rather than 6x100m 1-2 times a week on easy days, but hitting 800m sometimes even 400m pace on these strides, really focusing on form and turnover.