I purchased one of the Chapin 24v sprayers October 2017 (my wife even picked it up from the store for me!) so I haven't used it during prime growing season. I used it to spray my winter pre-ems, plan to spray my spring pre-ems soon, and plan to use it to spray PGRs. I am undecided whether I want to use it for spraying bifenthrin or imidacloprid.
First off - pesticides help but don't do all the work. I would argue that the ideal condition is to have such a lush and robust turf that it can fight off weeds and pests on its own or with minimal help.
Second - This may not apply to everyone but I think there's a progression of lawn-nerdiness/passion. I do believe that the warm-season 'bermuda' triangle will cover a lot and is a great starting point. The home owner can address problematic weeds as they arise.
I started off just using a hose end sprayer of weed-b-gon three way, glyphosate, and spreading granular fertilizer. Next came learning about granular pre-emergent. Then I discovered ATY and then this forum, which lead to learning about Celsius and Certainty.
Minimum - Glyphosate for spot application, prodiamine, and either a three-way amine or Celsius.
Next step (Sedge and Poa Annua) Certainty, Katana, Revolver, or Monument. Certainty is the lowest cost per app the last time I checked. I have Certainty for sedges and also did a broadcast app of Monument to control poa annua. My understanding is that Monument is the most effective on poa and Certanity is the least effective. I haven't used Katana or Revolver but have been told they are more effective than Certainty. I'd think Katana would be the optimal sweet spot in terms of effectiveness and considering cost per app. I don't think it plays well with St Aug though. @high leverage
may chime in with his $0.02 on this.
Nerd out level + $$$ = Rotating between methods of action on both your pre-and post herbicide to discourage herbicide resistance
pre/post (These are just examples, not a particular suggestion)
year 1 prodiamine (group 3 mitosis inhibitors) + 3-way (Group 4 synthetic auxin)
year 2 specticle (group 21 cellulose inhibitors) + hand brush glyphosate for all weeds (Group 9)
year 3 simazine (group 5 Photosystem II Inhibitors) + Celsius (Group 2 ALS + Group 4 synthetic auxin)
year 4 Oxadiazon (group 14 protox inhibitor) + Finale (Group 10 Glutamine Synthetase Inhibitors)
With that all being said here is my plan to spray:
Winter - Prodiamine, Simazine, and Monument (I want ALL the poa annua to die.)
Spring - Prodiamine and Simazine (Controlling spring flush of poa and getting ready for summer annuals)
Summer - Spot spray Celisus, broadcast spray T-nex PGR, hand-brush glyphosate, broadcast spray three-way if broadleaf weeds really become an issue