Even when the leaves are already in a pile it's quite slow and takes about an hour to collect a garden bag of mulched leaves. The thing claims 1:16 ratio but in practice it's closer to 1:6. So it's probably 5-10 minutes to suck in a bag of leaves already piled in one place.
The main problem is the obsession with grass.
Letting leaves kill my grass was a terrible mistake, I'll never make it again.
Seems like we decided arbitrarily on the most destructive form of yard that has secondary effects of causing scientifically proven damage to humans around us with sonic blasts from our leaf blowers.
Now, rake, blow, shake, snow, wait. That’s what grass needs and it is easy and looks good.
Or you go with artificial turf or something similar and that has its own issues.
For a lot of leaves, it's not a trivial amount of time. If that's your hobby, that's all good, but otherwise time is valuable and finite.
But ye, never understood the need for one. I am using a rake for 2000m2 of garden with 5 leaf trees. None of my 6 neigbours got a leaf blower.