Best Practice for Lead Management After Conversion

Hi John

After conversion Leads remain intact for historical purpose.

Some customers like to get some default predefined filter on Leads for ignoring converted ones.

Regards

Even for b2b the answer depends on sales cycle specifics and the modules employed to support it - whether the company uses Opportunities to manage long-lasting sales or prefers to maintain an Interest-To-The-Product cycle - from the first appearance of the interest and till the contract or lost.
For the last, the Lead-through-the-stages (LEad management) might work better than using Opportunities that may appear too complex structures (with numerous contacts, RLIs, QLIs, Purchases, etc) for managing Interest-To-The-Product cycle

It is pretty rare to ever use a Lead after conversion.

it depends on the Lead entity definition

in other words, it depends on the answer to a question what Lead differs from the Contact and why Lead is not a Contact but another entity

We suggest treating a Lead entity as an interest to the product articulated by the contact via the channel - 
that definition explains why Contact data may derive from the Lead data (name, title, etc - sometimes with enrichment during qualification) and that the Lead should also contain the description of the interest (text) or other impression of the interest (white paper downloaded)  and may have a reference to the product (or category of products).

Therefore, if salesreps deal with the interest in the product cycle , they may prefer to convert the Lead to the contact but keep working with the same interest and the same entity instead of creating Opportunity with all the excessive data.

Choosing the right data model and avoiding excessive data entering for unnecessary CRM objects is one of the keys to users adoption

I hope this makes sense