Alternating shoes allows shoes to dry/recover in between workouts. Stagger them so when one is half way through it's life, you introduce a new pair. Alternating also allows for your feet to get more time to get accommodated to the new shoe. If you have a race, worst case, you'll be able to wear only a half worn shoe, but I usually try to rotate in a new pair a few weeks prior to the race.

I used to get nasty blood blisters on my smaller toes - outside of pinky and in between pinky and next toe. I've also had a few regular blisters on my big toes during race training. About 4 years ago, I starting wearing toe socks on my longer runs and I have not had a blister since (https://www.injinji.com/). They are a little annoying to put on, but beats taping/band-aiding/lanacane coating my toes before runs. I still wear regular wicking running socks or even thinner athletic socks, but limit it to short runs or cross training activities. Lanacane anti-chafing gel is a pretty good product as well. Goes on dry and is more waterproof than other options (vasaline).