You'll reach a rhythm at some point and you'll probably be able to predict just about what you need to add, according to debris, sun and heat, and bather load. I'm a "jug dumper", only been doing it for less than a year (pool open year round) and I'm beginning to predict almost what I need to add without testing, but do test anyway, a few days a week, and keep FC at the upper level of my range most of the time.
Three main reasons I don't have and SWG, 1) I dump a lot of water to my lawn and woods backwashing (and the dogs splash-out a lot of water, which goes to beds and lawn, and don't want to put a lot of salt into the soil which is very alkaline) (we don't use synthetic chemicals and fertilizer out here, or other synthetics), 2) I have other priorities for monies going towards the pool (I just upgraded my pump to Intelliflo VF and Pentair Quad 80 DE, plus the labor, and have other things I want to do), 3) I'm here most of the time, home office, so I can keep close tabs on pool. We have to have a full time pet sitter when we are both gone so we get a free full time pool manager in the deal.
I live in woods, with high winds, with large amounts of plant debris (sized according to time of year) and boo-coos of bugs (we are in the roly-poly stage now - june bugs haven't hit yet). At first I was sweating the organics that the vac cleaner in-line, leaf canister and Pool Skim collected and was emptying them daily. Now that I'm not doing that I'm seeing that FC is holding well above minimum as long as I guesstimate it at top of range (or a bit over) when I add bleach every other day.
gg=alice