I think if you come in TOO quick behind the mower, the hay is still too "soft" to benefit enough from the tedder. Let it wilt a bit, and it'll remain standing "up" a little better and you'll get better air movement through it, for MORE BENEFIT from the tedding trip. They'll do a better job of clearing out any wet lumps this way too. If you come right behind the mower, the "lumps" will be too wet for the tedder to do as good a job on spreading/fluffing. Mine was a "reel type"... maybe the rotary units do a better job on this??? Never ran one of those.
I used to have the whole farm in hay, retailing it primarily to the horse market in small squares, and I was guaranteeing "no rained on hay". In SE Minnesota, that's a TALL order (we get pretty regular rains... and even MORE regular anytime you have hay down!
). I had 3 "fluffers" that I then hooked together behind 1 tractor, so I could do 30' in a pass. I would start cutting alot of times in the rain, just to get a jump on the weatherman. If he gave you a 4 day window, you KNEW you were gonna lose that last one, and I would try to pick up one on the front end this way. Cut today, by evening it's sunny and the hay is wilting good, tedd tomorrow morning when it's still slightly damp with dew, then rake and bale the next day. Always figured the tedders could take a day out of the drying time, and they would pretty much eliminate any wet lumps. If I was confident in the weather holding though, I'd try to avoid the trip with the tedders, unless I had a couple of really big days in the works. Had two NH balers and 15 kicker racks (18 footers) when we were going strong... we were putting up 30 - 40,000 bales a year, and delivering it all. MAN, am I ever glad I'm not doing that anymore!!! Talk about nerve wracking!
I still have the tedders, but haven't used them now for at least 10 years. Finally figured out that when you're selling hay, you're selling you're farm down the road one bale at a time. Now I try to avoid making hay if I can. Think I'm ahead to graze off everything as much as possible, and buy in hay if I need to, and then TRY to get the summer grazing/winter stockpile balance right. I've only been grazing winter stockpile now for 2 years so I'm a newbie on that front, and still have alot of learning room there, but I made it to the middle of December last year, and I'm not feeding any hay yet this year and the critters are happy and full, so I don't think I'm doing TOO bad at it. I've got plenty of hay on reserve for this winter, so I've got it covered either way.