The Problem: Missed injection, supply blocks, unused larvae. All leading to weak macro.
The Solution: Synchronizing all macro actions to larvae spawn cycle.
Larvae spawn is the lion share of Zerg’s production and occurs optimally in 30 second synced cycles over all your hatches. It is the heart beat of the swarm.
The Trick: Non-inject larvae appear every 11 seconds when you have less then three larvae, with the timer pausing when you do. So once your inject larvae pops and are used you will get a new one at a maximum of 11 seconds, if you make that into overlords ( 18 second to morph ) they will pop at the latest at 11+18 = 29, so exactly before your next inject batch pops.
In general you want to always make that first larvae in all your hatches into overlords, unless your are maxed out, highly over supplied or under serious pressure ( thou I would say that getting supply blocked is actually one of the most common ways to lose to all-ins ) that leaves us with 4-5 larvae per hatch per cycle ( it depends on the sync between the inject and natural larvae timings ideally 5-5-4 but due to delays in execution it gets closer to 4 )
The great majority of Zerg units are 2 supply which is a perfect fit for the 8 supply OV we are making ( 4 *2 = 8, Amazing! ). If however you are making pure lings/drones you can pass on every other overlord or even better, add queens. If your macro is perfect you will need to add an additional overlord made from your 2nd natural larvae every few cycles.
Creep is also on a 11 second timer, but a double one, 11 to build a tumor then 11 second cool down. To sync that we have two creep 'sides' and we alternate between them, and we go 0:11 -spread A 0:22 - spread B 0:33 - Spread A 0:44 - Spread B etc... we work that into the 30 second cycle by alternating ABA, and BAB every cycle. Creep spread timings are also a good time to check the mini map as you should be mini-map clicking to get to your creep edge.
Executing the cycle:
- Larvae spawns
1. Make army/drones with ALL your larvae
2. Inject all your hatches
3. Spread creep ( side A / B )
- 11 seconds pass till non-inject larvae pops ( 1 per hatch )
4. Make Overlords ( rally them to scouting locations )
5. Spread creep ( side B / A )
- 22 seconds pass till 2nd non-inject larvae pops ( 1 per hatch )
6. Make units - These 'off-beat' units are a great time to make units you want to place into non main army hotkeys ( infestors/ mutas/ etc... ), rally to special locations, replace killed overlords, add an additional overlord to buffer, sneak a few extra drones in zvz.
7. Spread creep ( side A / B )
- Larvae Spawns
tl;dr
when larvae inject pops, make only army/drones, then inject, then when the next non-inject larvae appear, make those into overlords and spread creep. when the next non-inject larvae appears, make special units and spread creep, rinse, repeat.