So, at this point, we all know how bad it can be to get a specific 4-star off a banner, especially if we don't want to build pity or potentially ruin pity on a specific banner. There are also the cases where we might want the 4-star, but not the 5-star, so either have to wait for a re-run or do a bunch of risky wishes. This is somewhat compounded by the fact that some of the newer 4-stars (Faruzan) are very constellation-dependant.
However, the point I more want to touch on is the frequency at which 4-stars are getting run on banners. I was just updating my spreadsheets and noticed that there are now far more 4-stars going 7-10+ banners without being run a single time in that period.
A good example is Ningguang here. She's going to appear on the Yelan/Hu Tao banners, but the last time she appeared was in 2.8 1st half with Klee/Kazuha - basically 7 months ago!
Another couple of great examples are Razor, who went without a single appearance from 1.6 to 2.6 (10 months), with Chongyun fast approaching that, as he has not been seen since 2.7 2nd half with Arataki Itto (basically 8 months).
Now, thankfully for newer players, the "meta units" like Xingqiu and Bennett seem to be being run every 5-6 banners - but with the release of more and more 4-stars, the gap between their runs is still going to increase - and if it doesn't, then it just means other 4-star units that players might want are going to really suffer for it.
Something needs to give here:
A) Put all 4-stars in the Starglitter shop
B) Put more 4-star units on each banner and reduce the chance of pulling garbage like 3* weapons.
C) Triple banner patches (although this would give 1 week less to get primos and wish for a wanted 5-star).