Where to add volume?

Currently on a TR road racing plan. The current build phase has my weeks at 1 Vo2 (1 hour), 1 sweetspot (1.5hr), 1 threshold (1hr 15min), and then I fill in another 4-5 hours of z2/tempo work.

Always looking to build volume and training load, so wondering where to add next. Not really time constraint at the moment, so I’m free to add anywhere. Just don’t know where it makes the most sense to add.

Should I bump up any of the interval session times? Throw in additional z2 or tempo time right after finishing an interval workout? Just looking for some suggestions.