Making a few assumptions on your question, I’m assuming a cycle is a completed project and “with 3-4 lot” references the project team size. And not knowing anything about the nature of the projects…
I think the answer to your question will reveal itself with some basic analysis/research on each project.
First, assuming no constraints (resources, etc.) what are the pure dependencies across all 80 projects? Are some of these infrastructure projects which must be done before others can even start? Ex: Roads, utilities, etc. Are some projects dependent on pieces of other projects completing? Or can all 80 projects run parallel with no cross dependencies? I think the first key step is mapping out these cross project relationships.
Second, what are the resource constraints? Not just personnel (skills set based, non-skilled, etc.), but also including things such as supplies, equipment, and consumed resources. Are there any constraints here? For example, each project needs bulldozers, but there are only 3 in total available. Each project needs plumbers, but there are only 10 available. Is the infrastructure available to ensure supplies are available when needed (this may identify risks). What are the key resources to keep the projects moving on schedule (building supplies, specifically skilled people, etc.)? Are there any known constraints to factor in from the start of planning? Meaning the sponsors already know there are only 6 total carpenters available to work across all 80 projects.
Third, what’s the estimated work for each major step of each project? And what is the anticipated resource needs for each step. For example, this step can reasonably estimated at 4 days with 4 carpenters.
Once you have these basics, you can start assembling a high level schedule (with generic resources) to construct the high level dependencies and concurrent resource needs, which will then provide the high level completion date of all 80 projects. That schedule should also show basic resource demands. For example, between month 12 and 16 we need 26 individual carpenters, but for the remainder of the project we only need 10.
After this is completed, the next question is if the high level schedule looks realistic. For example, we can complete this entire effort in 2.5 years assuming we have the number of resources and corresponding skill sets needed, building materials arrive when needed, and so on. Make a list of all these needs, all assumptions, and all dependencies that have been factored into the high level schedule.
Review that schedule and all that information with the sponsors to obtain buy-in. You may find that everything looks like it can be done. You may find that the 2.5 years is unrealistic, or you may also find there are new constraints you didn’t know of in this discussion. For example, we thought there were 10 carpenters, now it’s only 6.
This review my then lead to additional discussions. What are the key resource constraints driving the overall duration? Maybe it’s carpenters. Can we bring in additional carpenters to shorten the overall duration? This may lead to several what-if schedule scenarios. But in the end, it comes down to what the sponsors can accept. And at this point, there’s really only 3 options if the schedule can not be accomplished in the 2.5 years. Can the sponsors live with moving the target end date? Can costs be increased to add additional resources and bring in the target date? Do we need to cut scope (to complete in 2.5 years).
Hope this helps.