I'd say that many bloom for 6 months or more provided they are kept in a consistent environment.

Phalaenopsis Nancy Am x equestris. I suspect that equestris adds a bit of "easy growing" and branching spikes

In theory, some will bloom forever because they will bloom from a new flowering stem grown from a node.

This discussion will go on forever because some growers are quite happy getting a bloom no matter what.

Going back many years, I will relate the story of Betty, a lovely lady who was the Champion Orchid grower of a local Society. She had this species Phalaenopisis which was a sequential bloomer. It had a few dispirited blooms at the end of a long long spike and she would bench it month after month year after year to get a few benching points.

One of my Phals is about to bloom (pic. above) and after enjoying the blooms and benching it at a local orchid society for a few months and maybe putting it in an orchid show I am going to say thank you and go snip.

I has a few weeks to go before it blooms and has a secondary flowering spike forming so in theory it could be in bloom for ages.

Another grower has a Phal. House and belongs to many orchid Societies, he exhibits his orchids at various orchid shows over a period of about 3 months and at the end of the orchid show season he goes SNIP.

When I kept my orchids in one location, they would bloom really well, the flowers would last 3-4 months, and then be done. The spike would turn brown, and I would snip it. When I had to relocate them, they bloomed with far fewer flowers. However, when the flowers started fading, I noticed that about 2 months in, more buds started developing at the end. A month later, more flowers! Both times this happened, the second round had more blooms than the first. It happened to three different phals this way, and so I had flowers for about 7 months!

Honestly, I'd rather one fierce blooming, and then cut the spike. One of my phals would get branching spikes with 20+ flowers on it. It was glorious. This time it was only 7, followed by 12 flowers 3 months later. It's weird and I'm not sure why it's happening. Another is quite tiny but its flowers are small and gorgeous. It used to give 7-8 flowers. This time it was only 3. Followed by 4 a few months later. Since there were always buds, there was never an opportunity to cut the spike. It's odd.

As long as the spike is green it will make more buds, usually smaller flowers on the end of a long, bare spike. Not to my liking so I do as ArthurM, snip, snip.

I like to have new spikes with lots of flowers.

Choice is yours,

Jane