And there it is - predominantly I veg 4 weeks then flip. Fems go right to a 5g or 7g and for regs they don't get their pot until sexed so that knocks off a few weeks more of the soil being "used" Which means they can be good in a 5g if you know it's not a 12-weeker. If my plants are not rootbound (in one gallons) after I get the regs sexed they go to the 5'g. If they look "rooty" I'll shove them in a 7g. But pretty much anything going to flower from being "not to big" for a one gallon will not "eat" all of a 5g pot of good soil. I did a pair of 14wk Nigerian Ducksfoot in 7g pots and they finished faded but healthy faded. Nice fall colors.
It's all about what you grow for - and I grow for headstash.
I use homemade lacto bacillus, ferments from both ripe and green fruit and from ganja and comfrey, I'll add a little eggshell/vinegar calcium but never more than 4ml/gl of any of them. It is more to buffer the water and make the soil life happy than to feed the plant. That's whgat people don't get is that the food is already there, you just need to keep it watered, and those little treats supercharge everything.
If I really want to perk them up - usually right after flip - I'll add about a cup of worm castings to a 5g bucket and stir that occasionally for an hour or so. Or I'll sprout 2tbsp of barley or corn for a few days and blend that up as a sprouted seed tea. Or both. An alfalfa SST is great in veg. So there's always something to add to make us feel needed
I reamend with stuff from build-a-soil like their craft blend, or base minerals from down-to-earth, as well as my own vermi-compost from my "grass-fed" worms
The key is not a lot of anything, but a little of everything.