So It's hard for me to think on terms of veg and flower. My veg time is literally 10-14 days. I usually top dress once per cycle. Before flower. After that it's only green matter(leaves of cannibus or cover crop chopped and spread.
As far as ph. I'll be honest. I rarely ever give a second thought. I did check it last night randomly cause the wife And I were disputing that ph regulates itself on the mixrobial level. So I dropped the meter in and sitting st 6.3 ish. Now when I go a few More week and into flower my hypothesis is the ph will drop naturally to hang around 6.
So to answere I've never thought twice about mbp changing ph.
If I ever ran into any real problem then the first step would be bacteria dominant tea to bring ph up
The available of microbe food gives the steering wheel to the plant. Exudites are secreting and attract certain strains of bacteria which in turn fixate the elements needed at that particular stage of growth.
Also something about soil ph. It changes on a 24h period pretty dramatically. Even more when hand watering practices are used.
I own a grow store. I'm always so surprised and actually thought about the psychology behind the ph fanatics, were this train of throught Came from, and why people are so caught up on it.
imo ph should be thought about during soil build. By using proper ratios of buffers. I think our stoner minds get excited about the idea of doing something for the plant. And messing with ph is an easy way to give cultivators that daily feeling of "helping".
Any way. There's my coffee time gone for the day.
Cheers