Currently I have zero dirty screens and zero un-stretched frames...but that's because we've got some monster jobs on press. Ordinarily I try to keep well under 100 screens in the dirty screens rack. That's out of 600.
During times of year when we are doing tons of tiny jobs it can get up to almost 200, with the shop dropping off another set of dirty screens every 45 minutes or so. The one guy doing the cleaning is stuck at that station pretty much all day.
During times of year when all the presses are on huge runs we usually have the 'ready for press' rack stuffed with jobs and I try to keep 50 or so screens in the screen room just in case every single one of the four presses suddenly needs an entire setup.
We might be a big operation but I think the concepts scale up and down perfectly. I find it's all about keeping strategic buffers are specific points in the loop.
Buffer #1 - The screen room. Just in case a job suddenly needs to be prepared.
Buffer #2 - The ready-for-press rack. Just in case of a catastrophic failure in the screen department the presses won't stop spinning while I put out that fire.
Buffer #3 - The dirty screen rack. If this is empty then I have one guy with nothing to do. This is bad.
Buffer #4 - The reclaim room. That would be another guy with nothing to do. Also bad.
Buffer #1 and #2 are the most important. I imagine that would be universally beneficial in any size shop, as space constraints provide. Buffer #3 and #4 keep the workflow moving smoothly between all of the stations. If one of those runs out I put that guy on stretching and coating and have the guy running the CTSs just prep screens for developing. If that work runs out or another buffer runs out I then have them retension every screen that comes through--instead of just the ones that are over their retension date tag.
If a buffer runs out at one station that means there is a glut of screens somewhere else in the loop. So I bump the least busy guy up to the glutted station...except the only place in the loop we have no control is where the screens pass through the shop and get used...there are some times we are just at the mercy of the run size...then we do some house keeping...and if the runs are just that huge I start letting the guys duke it out over who gets sent home first. Anyone who really needs the hours I let stick around, but they have to indulge me and my R&D missions.