In microeconomics it is common to model utility decision between consumption and leisure. The latter refers to the time of a day the individual is not producing goods himself (if a yeoman producer) or to sell his labour in the market (a waged labourer). The productivity of the individual will affect how much it can produce (and earn) per unit of time. Therefore, time is directly incorporated into the model via productivity, which then affects the balance between consumption and leisure an individual will choose.
For example, consider a yeoman producer with the following utility function (yes, no Leontief, but makes the point):
$$ U(C,1-L) = C + a(1-L) $$
where $L$ refers to the proportion of the day the individual is working ($L \in [0,1]$).
He can produce with the following technology:
$$ Y = bL^h $$
and consumes all what he produces:
$$C = Y$$
Assuming the yeoman farmer is interested in maximising his utility, the unidimensional optimisation problem is:
$$ \text{max}_{_L} U(L) = bL^h + a(1-L) $$
The first order condition is:
$$ \frac{\mathrm{d}U}{\mathrm{d} L} = bhL^{h-1} - a = 0 $$
Thus, optimal proportion of time allocated to work is:
$$ L^* = b^{\dfrac{1}{1-h}}\left(\frac{h}{a}\right)^{\dfrac{1}{1-h}} $$
Optimal consumption is:
$$ C^* = b^{\dfrac{1}{1-h}}\left(\frac{h}{a}\right)^{\dfrac{h}{1-h}} $$
The effect of (labour) productivity on hours of work depending on the returns to scale of technology ($h$). You have that:
if $h \in (0,1)$, a ceteris paribus increase in $b$ means the individual works and consumes more.
if $h > 1$, a ceteris paribus increase in $b$ means the individual works and consumes less.
if $h = 1$, productivity might not affect labour at all (but does affect consumption). In this case, there is a corner solution for labour ($L^*=1$ or $L^*=0$). I leave this as an exercise.
So, you are concerned about "the time to produce output". Well, think of $b$ as an indication of how much time you can spend to produce a given amount of output with a fixed amount of labour. As I indicate above, variations in $b$ have important consequences for $L^*$, $C^*$, and ultimately for maximum utility $U(C^*,L^*)$.
Note: The specification I chose means the income and substitution effect arising from an increase in productivity ($b$) do not cancel each other. Other utility function (e.g. with $\ln C$) will mean $b$ does not affect $L$. I also leave this exercise to you.
