I watched the first two nights of Jimmy Fallon’s “Tonight Show,” and he seems to be doing fine. Those who liked him on “Late Night” will still like him an hour earlier, and time will tell if Jay Leno’s fans will continue to tune in to NBC for Fallon in that slot (or at least set the DVR).

Normally, I wouldn’t critique a host (TV or radio) based on their first week, because it always takes time to find the groove, to winnow down the big list of seemingly clever ideas the staff had before the debut to see what works and what doesn’t. That doesn’t apply to Fallon, who has five years of experience doing this kind of talk show, so what we’re seeing now is pretty much what we’ll get — minus the nervousness brought on by the hype.

The most important thing for a host to remember is that, no matter how good or bad yesterday’s show was, you have to do a new one today, and tomorrow, and so on. There have been days when I walked out of my studio as high as a kite from a show that was even better than I expected, and there have been days where I walked out depressed and pissed off. But I always try to remember that I’ll have to do something new the next day. No one can be great every time, and no one in the history of broadcasting ever has. Fallon has to continue to prove that he’s adept at the hosting duties, can come up with new material that goes viral, and will keep the traditional late night talk show landscape mostly undisturbed.

However, I think he’s making a mistake by following Jay Leno’s advice that he do a longer monologue. When Leno took over from Carson, his monologue was about the same length as his predecessor (5-6 minutes), but after a few years, he expanded it to about 10, and sometimes as many as 13 minutes. That did not make the monologue better. As good as Leno is as a joke-telling standup comedian, his expanded monologue always seemed like it was padded, and he relied too heavily on over-selling the jokes and playing to the band. It didn’t help that audiences were so pumped up that they’d laugh at anything he said.

Letterman extended his monologue, too, when he moved from NBC to CBS, but that never yielded anything particularly memorable. Naturally, the hosts who followed them with their own shows at that hour followed the lead of the twin kings, so that on many nights, you have as many as five white guys telling essentially the same jokes about the same items in the news. Ironically, none of them are ever as funny and biting as the two guys who consistently deliver laugh-out-loud comedy in late night — Jon Stewart and Stephen Colbert — without doing what can be considered a traditional monologue.

Bill Maher has been a standup comedian for decades, so he knows how to get the job done, and he has a staff that’s quite good at writing in his unique voice. I enjoy him, although he has two very irritating habits. One is that he laughs at his own jokes more than anyone not named Arsenio. The other is that, when a joke doesn’t work, or doesn’t get the positive reaction he expects, he blames the audience. Last Friday night on “Real Time,” he did a line that got no response at all and — unlike his hero, Johnny Carson, who was a master at saving such situations — Maher lashed out cursed at the crowd as if it were their fault. It’s never appropriate to blame your fans when you blow it.

The biggest problem in Fallon doing an extended monologue is that he is not a standup. Yes, he’s a gifted enough impressionist that he can imitate a comedian, but it’s clear that his strengths lie elsewhere. Although NBC would no doubt have balked at the idea, it would have been refreshing to see him start “The Tonight Show” with a shorter monologue and then get on to parts of the show he enjoys more (and is better at delivering).

Last night, Jerry Seinfeld came out and did several minutes at center stage and killed. Then, in a nod to the past, Seinfeld stayed at the microphone and glanced over at Fallon, who waved him over to the guest chair. When he got there, Seinfeld acted the way he did the first time Carson made that same gesture. It was a nice tribute to “Tonight Show” history.

Fallon should give more standup comics that opportunity. Sure, Seinfeld is one of the greatest monologists of all time, so we can’t expect that level of quality from everyone, but it would be nice to see the current generation of standups getting the same kind of big network platform that Carson gave Seinfeld so many years ago.

There would be plenty of time for that if Fallon cut down his own monologue.