That's a perfectly fair point, shep53. The fluke becomes an adult at 8 weeks old, so a med that kills only adults will need repeating every few weeks to keep killing all flukes. A med which kills larvae can be repeated less frequently - at least 8 weeks cover is given by one dose of a flukicide which kills all larvae.
You are correct to state that there is a type of infection (acute fasciolosis) in which the damage is done by the larval stage. Our vets around here do not talk about acute fasciolosis being an issue - jacob you should be advised by your vet as to whether you need to be concerned about this.
Combinex and Fasinex contain the same flukicide (triclabendazole.) Combinex includes a wormer as well, which jacob was wanting. Both have a 56 day withdrawal and both kill susceptible flukes as young as 2 days old, so do not need repeating more frequently than every 7-8 weeks.
Flukiver is for fluke only, not roundworms. It kills immature flukes down to 3 weeks old but is not highly effective on flukes younger than 4 weeks old. It has a 42 day withdrawal period.
Trodax again is not a broad-spectrum wormer, it is primarily for fluke. It claims to be effective against fluke larvae as well as adult fluke. It recommends routine treatments at no more frequently than 7 week intervals.
Albacert, Albex, etc, contain albendazole, which is effective against adult flukes, not larvae but does kill fluke eggs. In order to maintain protection on fluke-infested pastures, dosing is usually repeated every 6-8 weeks. The advantages are that the withdrawal is only 5 days, so fat lambs can be sent away as soon as ready, and that it also kills a broad spectrum of roundworms.
I suspect that this is not helping jacob very much - sorry, jacob - but fluke is a complex disease!
The precis is that if you want to kill worms and fluke with one dose, use Combinex or Albacert. There could be a risk of an acute form of the fluke disease if you use Albacert - check with your vet if this is an issue in your area. If you use Combinex, you cannot sell the lambs into the fat within 8 weeks of treatment. (With Albacert it's only 5 days.)
Do check if you need to be worried about fluke in your area - if not, tell us and ask again about advice on wormer-only products!
HTH
Sally